A bomb exploded outside the offices of Greek business federation in central Athens early on Tuesday, police officials said.
Attacks against banks, politicians, journalists and businesspeople are not uncommon in Greece, which has a long history of political violence and has been mired in its worst economic crisis in decades.
Police believe the blast was carried out by domestic guerrilla groups, is the first such attack since leftist Prime Minister Alexis Tsipras came to power in January.