A homemade explosive device went off early Thursday in front of a church in central Athens injuring a police officer but there were no immediate claims of responsibility.
The explosion happened at 7:10 am (0510 GMT) in the upmarket Kolonaki area, police said, adding that an arterial road had been sealed off.
The police officer was hospitalised with minor injuries.
Non-fatal attacks targeting centres of power and embassies have been common in Greece in recent years, often blamed on anarchists or far-left groups.
Ten days ago, a homemade bomb exploded outside the headquarters of the Skai media group in a seaside Athens suburb causing major damage. There have been no claims of responsibility.