At least four men tried to drive a car at the embassy compound around 10 a.m. but were gunned down by guards, CNN reported. A fifth attacker was wounded and in custody, officials said, but no U.S. Embassy staff members were injured.
Witnesses said after the initial exchange of fire, two of the attackers fled to a nearby building but were chased and gunned down by security forces.
The BBC said TV footage from the scene showed pools of blood on the pavement and what appeared to be bomb parts using pipes and gas canisters.
Without naming sources, Israel's Arutz Sheva broadcaster said "Western sources are not convinced the incident was not staged" to show the United States that it, too, is fighting terrorism.