Several gunshots were fired from a vehicle at the US embassy in the Turkish capital, Ankara, on Monday, hitting a window in a security cabin but causing no casualties, Al Jazeera reported.
The attack coincided with a deepening row between Ankara and Washington over the trial of a US pastor in Turkey.
A police officer told Reuters news agency at the scene the drive-by shooting occurred around 5am (02:00 GMT) and that nobody was hurt.
The embassy was set to be closed this week for a public holiday to mark the Eid al-Adha festival.
Police teams were searching for the assailants, who fled in a white car after the attack, CNN Turk said. Four or five gunshots were heard, it said.
Ties between Ankara and Washington have strained over the case of US pastor Andrew Brunson.