Evan Fournier poured in 28 points for the French as the Americans, who have won gold in the past three Games, were beaten for the first time since 2004.
A strong third quarter, where France outscored Gregg Popovich's star-studded team 25-11, proved decisive.
Rudy Gobert was also influential with 14 points and nine rebounds.
It was a disastrous start for Team USA who struggled in their preparation for the tournament, losing warm-up matches to Nigeria and Australia.
They looked to have taken control of the game with an eight-point half-time lead.