One of the home-made explosives damages a car parked at the home of an embassy staff, the other fails to detonate.
Two explosives have been targeted at cars belonging to the Italian embassy in Greece, one of which went off without injury, Greek police said.
Responsibility was not immediately claimed and officers said they were investigating the investigation.
A homemade bomb exploded at about 4 am (02:00 GMT) on Friday, damaging a vehicle parked at the home of an embassy worker in a suburb of Athens, police said.
The other device, placed near a second diplomatic vehicle, did not go off.
Italian Prime Minister Giorgia Meloni expressed “deep concern” over what she called an “attack … probably of anarchist origin”.
The far-right leader sent her “personal thoughts and those of the Italian government to the first adviser of the Italian embassy in Athens, Susanna Schlein”.
Meloni added that she was following the matter “with the utmost attention” through Foreign Minister Antonio Tajani, who was in Athens for talks on Friday.
The Greek foreign ministry “strongly condemned the attack” and said such “unacceptable” acts “would not disrupt the excellent relations and bonds of long-standing friendship between Greece and its partner and ally Italy”.
Crude, homemade devices, which cause damage but rarely injury, are often used against political or diplomatic targets, banks or foreign companies in Greece.
The police often blame groups of the extreme left or anarchists.