The US team, which downplayed the political aspect of the matchup, methodically pulled away in the first half, wearing down the Asian champions with its depth and athleticism.
Kevin Love scored 13 points and Kevin Durant 12 for the Americans (4-0), who will meet the fourth-place team from Group A in the round of 16.
The tensions between the nations' governments provided the backdrop off the court, where before the game a group of fans sitting near midcourt held US and Iran flags with a sign reading "PEACE" in between.
But the only sparring on the floor was a playful bump between Haddadi and US forward Rudy Gay, teammates with the NBA's Memphis Grizzlies.
The countries have feuded for decades and their relations have further deteriorated in recent years, with the United States sanctioning Iran for continuing with programs it believes could be used to create nuclear weapons.
After playing his starters for most of the second half of a 70-68 victory over Brazil on Monday, US coach Mike Krzyzewski went to the bench early in this one, with the Americans shooting 58 percent and scoring 23 points off turnovers in the easy victory.
Hamed Haddadi scored 19 points for Iran (1-3) and Arsalan Kazemi had 14.
The US team tried to keep the focus on the floor, with Krzyzewski saying he had played in Iran in the 1970s with an Armed Forces team and had great respect for the country.
"We are just here to play basketball," Durant said Monday. "The political situation is something we cannot control. We have to go and just play the game of basketball." There's no rivalry on the basketball court, where the nations had never met in Olympic or world championship play. The Iranian national team even came to Utah two years ago at the invitation of the NBA to play in a summer league as preparation for the 2008 Olympics.
And in a nod to the Iranian supporters in Istanbul — which included minister of sports Ali Saeedlou earlier in the tournament — dancers were ordered to cover up for their performances during the game. Iranian women aren't allowed to show skin in public, and Iranian officials had turned their backs when the dancers performed in earlier games.
The dancers wore long pants Wednesday.
Iranian fans, many waving flags and chanting, had plenty to cheer early. Haddadi won the opening tip, Durant fired a pass behind Andre Iguodala and out of bounds on the Americans' first possession, and the US lead was only six after one quarter.
But the Americans quickly pushed it into double digits in the second and gradually extended it to 14 at halftime, then opened the second half with another burst to push it past 20 and turn Group B's second game of the night into a dull affair.
Following Thursday's game against winless Tunisia, the Americans will have three days off before playing Monday against an opponent still to be determined. But a difficult quarterfinal could follow, with Spain looming as a possible opponent after two surprising losses have dropped the defending world champions into third place in their group.
The Americans want to have their reserves playing well by then, and all 12 players scored Wednesday. Derrick Rose was the only other player in double figures with 11 points.
 

In Izmir, Jonas Maciulis had 19 points and Linas Kleiza added 15 points as Lithuania beat France 69-55 Wednesday to clinch top spot in Group D at the basketball world championship.
Lithuania (4-0) handed France (3-1) its first defeat and, after playing Lebanon (1-3) on Thursday, will face the fourth seed of Group C - likely Greece, Russia, China or Puerto Rico - in Istanbul on Tuesday.
Nicholas Batum scored nine points in the first quarter as France jumped out to a 24-11 lead with an 11-0 run.
Down 30-24 at halftime, Lithuania took a 35-32 lead three minutes into the third on Martens Pocius' three-pointer. It built its lead as France missed eight of 13 field goal attempts and three of four free-throw attempts in the quarter.
Kleiza took a half-court pass on a fast break to dunk with 4:42 left in the quarter, giving Lithuania a 44-35 lead and sending a group of fans wearing yellow wigs and green smiley-face T-shirts to their feet.
At times, it seemed as if all the basketball-crazed Baltic country's faithful made it to Halkapinar Arena for this one. They hung at least 20 flags from the rafters, and brought out about 10 more to wave during the breaks. Behind one basket, a section of the fans periodically unfurled a giant rectangular swathe of green, yellow and red-colored cloth that blocked the sight of at least 80 people.
Back-to-back three-pointers by Tomas Delininkaitis and Renaldas Seibutis gave Lithuania a 58-41 lead with 7:30 left in the game, and France never got within 10 after that.
France plays New Zealand (2-2) Thursday.
 

In other games, Marc Gasol led defending champion Spain into the second round, scoring 25 points Wednesday in a 91-57 rout of Lebanon in Group D.
Spain (2-2) has struggled in Turkey but built a double-digit lead in the second quarter and was never threatened the rest of the way. It was Lebanon's third loss, eliminating it from the tournament. France, Lithuania and New Zealand will join Spain in the next round.
Jackson Vroman had 22 points for Lebanon, including 12 in the first quarter as the underdogs took a 22-21 lead. But things unraveled from there as Gasol, Fran Vazquez and Jorge Garbajosa started to get the Lebanese big men in foul trouble. Spain went on to outscore Lebanon 42-10 in the paint the rest of the way.
"We finally loosened up with fast breaks and attacking their zone," Spanish coach Sergio Scariolo said.
Vazquez had 15 points for Spain.
Lebanon coach Tab Baldwin said his players "didn't just play a first quarter in this game." "After that we fought very hard. Eventually just the weight of Spanish basketball — the size, the skill, the speed — became too much to bear," he said.

In Kayseri, top-ranked Argentina won its fourth straight game by defeating winless Jordan 88-79.
Luis Scola scored 30 points, his third straight game with 30 or more, and grabbed 13 rebounds. Carlos Delfino added 18 points. Rasheim Wright had 22 for Jordan and Ayman Idahois scored 20.
Argentina never trailed, led by as many as 20 and did just enough to hold off Jordan in the fourth quarter. Argentina plays Serbia on Thursday for first place in Group A.
 

In Ankara, host Turkey maintained its perfect record by narrowly beating Puerto Rico 79-77 Wednesday, despite trailing its rival in the first three quarters.
Hidayet Turkoglu of Phoenix Suns led Turkey (4-0) with 16 points and Ersan Ilyasova of the Milwaukee Bucks had double-double with 13 points and 13 rebounds as the host team pulled away in the last quarter.
Puerto Rico (1-3), which desperately needed a win to guarantee a spot in the second round, squandered a three-quarter lead over Turkey.
Kerem Gonlum put Turkey ahead with a basket at the beginning of the fourth quarter and added one more point from a free throw. And Ilyasova scored a three-pointer seconds later to increase the difference to five points, putting Turkey ahead after a long lull as nearly 10,000 Turkish fans burst into cheers. Turkey never looked back.
Jose Barea squandered a counter-attack for Puerto Rico with an offensive foul as Ender Arslan answered with a two-point basket and Turkey's Kerem Gonlum had a following slam-dunk. Semih Erden's tip-in at 7:15 further widened the gap to nine points.
Hidayet Turkoglu hit a three-pointer at 5:01 for Turkey which was immediately responded in the same way by Nathan Peavy. But Turkey's Tunceri scored a free throw to set the score 79-77 with just six seconds to go.
 

Olimpio Cipriano scored 30 points as Angola rallied from a 10-point deficit late in the game to stun Germany 92-88 in overtime and advance to the round of 16 on Wednesday.
Angola began the tournament by losing by 50 points to Serbia but improved with every game and capped its run by beating Germany for the first time. Germany (1-3) was eliminated.
Jagla's 3-pointer made it 74-64 to Germany with 3:56 minutes left on the clock.
But Angola wasn't finished.
Gomes sank a 3-pointer to put Angola within six, Felizardo Ambrosio stole the ball for a dunk and after both teams wasted their next two possessions, Ambrosio made another 3 to make it a one-point game. Heiko Schaffartzik made one free throw but Cipriano sank both to send the game into overtime.
In overtime, Schaffartzik's 3-pointer got Germany within three with seconds remaining, but Ambrosio then made both free throws to secure the win. Ambrosio finished with nine points and seven rebounds.
Magalhaes said his team had tried to stay in the game even when it fell 10 behind.
Germany's only win before Thursday's final game against Jordan had come against Serbia.
Serbia, Argentina, Australia and Angola will advance from Group A. Serbia and Argentina will decide the pool winner on Thursday.
 

Greece secured a spot in the second round and eliminated Ivory Coast with a 97-60 win on Wednesday, spurred by 15 points from Nick Calathes.
A day after a disappointing 76-65 loss to rival Turkey, Greece (3-1) took a commanding lead from the start to hand Ivory Coast its fourth straight loss. Kostas Tsartsaris and Georgios Printezis had 12 points each for Greece and Calathes had eight assists.
"After a crucial game against Turkey that we could not win, we talked and said life goes on and we have to keep playing and that is what we did today," said Greece forward Kostas Kaimakoglou. "We showed we are in good shape for our next game against Russia. The most important thing is to be ready for the next round." Ivory Coast jumped out to a 7-0 lead, but it was all Greece from there. The Greeks went into halftime with a 47-19 lead and increased the gap to 43 points in a fast third quarter that ended 81-39.
The Greeks played with black strips on their jersey as a sign of mourning for Andreas Miaoulis, the president of the Greek basketball federation, who died Tuesday in Athens.
The match started after a minute's silence in memory of Miaoulis, who held the highest post at the Greek federation since 2002. He was 72 and suffering from cancer.