Turkey says it was forced to ease border controls for refugees as it did not receive sufficient support to host them.
"There was only one step left for Turkey to take in an environment where it is left alone in hosting refugees and averting terrorism," said Fahrettin Altun, Turkey's communications director.
Turkey, which hosts 3.6 million Syrians, "has no other choice" but to ease its efforts in containing the refugee influx pressure, Altun said, after the military escalation in Syria's Idlib province.
"It should be known that the Syrian refugees are now a problem for not only Turkey but the whole world, in particular the countries in the region and Europe," he said, according to state news agency Anadolu.
Turkey does not believe its decision to allow some of the millions of migrants it hosts to cross into Europe will have an impact on its ties with the West, the communications director said.
In response to the escalating conflict and the killing of 33 of its troops Thursday in Syria's Idlib region, Ankara threw open its western land and sea borders to outgoing migrants.
Turkey, which is already home to around 3.6 million Syrian refugees, fears more people arriving in the country where there is growing popular discontent against their presence.
In a series of tweets, Erdoğan's top press aide, Fahrettin Altun, accused Bashar al-Assad of "conducting ethnic cleansing" and seeking to drive millions of Syrians out of Idlib.
"These people will try to escape to Turkey and Europe. Already hosting close to 4 million refugees, we do not have the capacity and resources to allow entry to another million," he wrote.
Greece and its EU partners also fear another influx of refugees from Syria after more than one million made their way there in 2015 before an EU-Turkey accord was reached on controlling the numbers.
