“On the orders of the president … permission will not be given for migrants to cross the Aegean Sea because it is dangerous,” the coastguard was quoted as saying by Anadolu news agency late Friday.
On Saturday tensions flared on the Greek-Turkey border where tear gas and smoke bombs were fired at thousands of migrants amassed at a makeshift camp waiting to cross into Europe.
Greek soldiers and riot police have been manning the borderland, as thousands of migrants have made a rush for the frontier in the past days. Their Turkish counterparts have been stationed on the other side.
Turkey said on February 28 that it would let migrants cross its borders into Europe, saying it could no longer contain the tens of thousands who have been trying to cross since that date, nor a potential fresh influx of migrants due to intensified fighting in northwest Syria.
Turkey on Friday accused the European Union of using migrants as political tools after EU foreign ministers said they would work to stop illegal migration into the bloc.
The EU on Friday pleaded with migrants on the Turkish border to stop trying to cross into Greece but dangled the prospect of more aid for Ankara as a standoff entered a second week.