Damian Lillard led the way for USA with 21 points at Saitama Super Arena.
Mohammad Jamshidi and Hamed Haddadi shared a team-high 14 points at the losing end. Navid Rezaeifar followed with 13 points.
USA faces the Czech Republic on Saturday to wrap up its Group A fixtures. A potential win would clinch a quarterfinal berth.
Iran, who lost to Czech Republic in its first match, needs to beat France in three days and hope for favorable results elsewhere to progress.