Shots were fired early Monday at the German ambassador's residence in Athens, police said.
The bullets were fired from a Kalashnikov assault rifle at the residence of Wolfgang Doldt in the Athens district of Chalandri at 03:03 am (0103 GMT), dpa reported.
No one was injured in the attack, a police spokesman said.
Anti-terrorism police arrested three people, said press reports.
The residence's police guard reportedly did not use his weapon due to concern for neighbouring residents.
At least 20 shots were fired, according to a report by the radio station Skai. Four bullets reportedly lodged in the garden gate. The police spokesman did not comment on the details of the attack.
Greek Prime Minister Antonis Samaras and Minister of Public Order Nikos Dendias have spoken by phone with the German ambassador.
The German ambassador's residence was the target of a terrorist attack in 1999 when an anti-tank weapon was fired at it.
Many in Greece blame Germany's stance on austerity measures for their ongoing economic troubles.