The quake was centered in the town of Lixurion, on the Ionian island of Cephalonia, the U.S. Geological Survey said.
Lixurion is a coastal resort area outside the island's main town of Argostoli.
Ekathimerini.com said the tremor was felt as far away as Athens. The report said the European-Mediterranean Seismological Center pegged the quake's magnitude at 5.7.
There were no immediate reports of any damage or injury.
Justin Bieber crashes Drake Bell's album release party
Rosie O'Donnell unveils nearly 50-pound weight loss