Erdogan said talks with Moscow over the past fortnight had so far failed to achieve "the desired result" and warned that Turkey would launch an offensive into Syria unless Damascus pulled its forces back by the end of the month.
"An operation in Idlib is imminent... We are counting down, we are making our final warnings," Erdogan said in a televised speech.
He called for Syrian forces to retreat behind Turkey's military posts in Idlib, which were set up under a 2018 deal with Russia designed to hold off a Syrian Army advance.
Turkey, supporter of some militants groups in Syria’s northwestern Idlib Province, has been pushing for a renewed cease-fire in talks with Russia, which backs the Syrian government. Ankara is eager to prevent another flood of refugees into its territory adding to the 3.7 million Syrians it already hosts.
The Kremlin quickly responded to Erdogan's threat, warning that any operation against Syrian forces would be "the worst scenario."
With Turkey moving large numbers of reinforcements into Idlib in recent weeks, Defense Minister Hulusi Akar emphasized that it was "out of the question for us to withdraw from our observation posts."
"If there is any sort of attack against them, we will retaliate in kind," he told reporters in Ankara.
Iran offers good offices
Iranian Foreign Minister Mohammad Javad Zarif said Syria and Turkey can resolve their issues related to Idlib through the good offices of the Islamic Republic.
“We are prepared to hold talks with our Syrian and Turkish brothers about Idlib at various levels,” Zarif said on the sidelines of a weekly cabinet session in Tehran on Wednesday.
He also emphasized that the previous agreements about Idlib and the fight against terrorism must be implemented.
“The Syrian government must be able to ensure the security of its citizens,” he said.
“If they need to use our good offices, this problem (in Idlib) will be resolved with less harms,” Zarif said.
He also unveiled plans for a new meeting of the Astana peace process among Iran, Turkey, and Russia in the near future.
Syrian troops have reconquered swathes of Idlib and retaken the key M5 highway connecting the country's four largest cities as well as the entire surroundings of Aleppo city for the first time since 2012.
Government forces made new gains in western Aleppo Province on Tuesday and were pushing toward the Sheikh Barakat mountain.
That would give them a vantage point over large parts of Idlib and Aleppo provinces, including sprawling camps housing tens of thousands of displaced people.
AFP and Tasnim contributed to this story.