State Department spokeswoman Victoria Nuland said the film, first Iranian film to win Oscar, "really gives the world an invaluable picture of life in Iran".
"We applaud his achievement and celebrate the vibrancy and historical greatness of the independent film industry in Iran," Nuland told reporters.
Children of Heaven in 1998 was the only other Iranian film which had been nominated for Best Foreign Language Film.
The widely-hailed movie also won the best foreign film at the Golden Globes.