Makeshift bombs exploded outside the homes of five Greek journalists in attacks claimed by an anarchist group, which said it was protesting at media coverage of the economic crisis.
The incendiary devices caused minor damage but no injuries.
They were the first coordinated attacks against mainstream journalists since the Greek debt crisis erupted in 2009.
In an internet statement, the anarchist group that goes by the name 'Lovers of Lawlessness' said of the journalists: "While they use a pro-workers rhetoric, they wink mischievously at their political bosses."
Police said the group has used such devices - gas canisters and explosives packed together - in the past.
Among those targeted by the bombs were the editor of the semi-official Athens News Agency and two presenters from the private television channel Mega.
Homemade bomb attacks have been on the rise as Greece struggles through its sixth year of recession.
The recession has fuelled anger against foreign lenders, the wealthy elite and mainstream media, who are viewed by Greeks as close to the political classes.
The Greek government condemned the attacks, which followed scattered protests against a police raid earlier this week to clear a squat popular with radical leftists and anti-establishment groups.