A group of anarchists threw paint and a smoke bomb at the official residence of the US Ambassador to Greece, Geoffrey Pyatt, in central Athens in the early hours of Wednesday.
According to preliminary reports, the group drove up on motorcycles to the residence, which is near the US Embassy, and immediately fled after the stunt.
At least seven suspects have been arrested.
The Rouvikonas (Rubicon) anti-establishment group claimed responsibility and has released a video of the attack.
It is the third time that the ambassador’s residence has become the target of anarchist groups.
Ambassador Geoffrey Pyatt said in a tweet Wednesday that the paint attack was “childish vandalism” and that he would work with Greek authorities “to punish the culprits according to law.”
The ambassador said “destruction of property is not peaceful protest.”
The Greek foreign ministry also condemned the attack, saying it was an “unacceptable and irresponsible act that will, however, not harm the friendship and increasingly broad cooperation between our two countries.”
On Tuesday evening, anarchists firebombed the headquarters of the socialist PASOK party in central Athens, following a march to demand a prison furlough for convicted terrorist assassin Dimitris Koufontinas.