"More than 80,000 brothers from Idlib have started marching towards our border," he said during a speech in Istanbul, pointing out that Turkey will not bear the burden alone.
"The unfavorable consequences of such a pressure with which we could be confronted would also be felt by all European nations," said Erdogan, who frequently accuses the European Union of a lack of actions to support Turkey in the refugee crisis and threatens to send Syrians into the EU.
Erdogan gave no details on whether any of the refugees had reached the Turkish border.
The Syrian northern province of Idlib is the last main rebel-controlled area in Syria, where government forces backed by Russia conduct airstrikes against rebel targets.
Turkey hosts 3.6 million Syrian refugees, making the country the world's top refugee-hosting nation.