Israeli gunboats randomly fired at the Palestinian vessels off Beit Lahia in northern Gaza city on Wednesday, forcing the fishermen to get out of waters, local sources said.
No casualties were reported.
Israel had imposed a limit of three nautical miles on fishing in waters off the Gaza shore until last August.
Under a ceasefire agreement reached between Israelis and Palestinians in August 2014, Israel agreed to immediately expand the fishing zone off Gaza coast, allowing fishermen to sail as far as six nautical miles off the shore.
Palestinian fishermen, however, say that the Israeli navy opens fire before they reach the agreed upon limit.