The earthquake occurred yesterday at 11:30 pm local time off the southern coast of Crete, at a depth of 10 kilometres.
The Institute reported that the epicentre is near the coastal town of Ierapetra and about 60 kilometres southeast of the island's largest city, Heraklion.
Although the temblor was felt strongly in the eastern part of Crete, according to local media, no casualties or damages have been reported so far.
Three aftershocks, each of a magnitude of 3.5, have occurred within half an hour of the main quake.