Four armed Islamic militants tried to storm the embassy compound Tuesday morning, a day after the world marked the fifth anniversary of the September 11 attacks on New York and Washington.
A ministry spokesman told RIA Novosti the terrorists parked two rigged vans outside the embassy and planned to storm the compound after detonating them.
Minutes after opening fire on security guards at the embassy's front gate, however, a Syrian anti-terror unit arrived at the scene. They killed three of the attackers, wounding one, and diffused the bombs.
The gunmen had a large number of hand grenades on them, which they tried to throw over the compound's walls, the official said.
He said no organization had claimed responsibility for the attack so far, and that investigators were working to establish the assailants' affiliation.
The U.S. embassy is based in a heavily-guarded area of Damascus, along with other foreign diplomatic missions and a Syrian presidential residence.
Washington withdrew its ambassador from Damascus several days after former Lebanese Prime Minister Rafik Hariri was killed in Beirut in February 2005, blaming the assassination on Syria.
The attack came amid growing anti-American sentiment over the Israeli-Hezbollah conflict in Syria, a staunch supporter of the Lebanon-based radical Islamic movement, which has been designated by the U.S. and other Western countries as a terrorist organization.