Gunshots were fired at the US embassy in the Turkish capital, Ankara, early on Monday, police said, in the midst of a diplomatic crisis that has enraged many Turks.
Police said no one was hurt in the incident and the embassy was due to be closed for the Muslim Eid al-Adha celebration.
Broadcaster CNN Turk reported a search was ongoing for the assailants, who fired several shots from a vehicle.
Turkey's economy, and its currency in particular, has been shaken by US sanctions designed to force the release of detained American pastor Andrew Brunson.
Turkey has promised to respond to the sanctions and resisted releasing Brunson, who is accused of being involved in the 2015 coup attempt, unless the US makes concessions to Turkey.
Incensed by the US measures, some Turks have protested by uploading videos of themselves burning US dollars and smashing iPhones to social media.
The US embassy in Ankara and the consulate in Istanbul have been the targets of attacks by militants and have faced numerous security threats in the past.