Ten people had been rescued and another three were believed to be missing, AP quoted Greece's coast guard as saying.
Two coast guard patrol boats, a vessel from the European border agency Frontex, one helicopter and two aircraft, as well as a vessel that had been sailing nearby, were involved in the search operation, the coast guard said.
According to the Greek coast guard, the dinghy appeared to have sunk inside Turkish territorial waters, with initially one survivor swimming into Greek territorial waters and being picked up by Greek authorities. Another nine people were then also rescued, they said.
Survivors told authorities there had been a total of 13 people on the dinghy when it sank. Their nationalities weren't immediately available.