A Turkish coast guard vessel rammed a Greek vessel near the islets of Imia in the early hours of Tuesday, according to Greek media.
There are no reports of injuries to the crew of either boat. The Greek vessel suffered minor damage.
Greek defense sources say that in recent weeks Turkey has increased its coast guard presence around Imia.
They add that, respecting the principle of proportionality, Greece has deployed only coast guard vessels and refrained from sending warships to the area.
The latest incident at Imia follows a series of what Athens says are Turkish provocations aimed at disputing Greek sovereignty.
Imia in 1996 was the scene of a tense standoff between Athens and Ankara which almost lead to a full-scale war between the two NATO allies over sovereignty issues in the Aegean.
In January, Turkish media claimed that the country’s navy blocked an “assault boat” carrying Greek Defense Minister Panos Kammenos from approaching the islets to lay a wreath.
A few days later, a senior adviser to Turkey’s leader Recep Tayyip Erdogan said any foreign political or military official who steps onto Imia will have their arms and legs broken.