Turkey's Defense Ministry on Friday called on all parties to any move that will climb the instability in Manbij, northern Syria.
"We warn all parties to stay away from provocative actions and rhetoric that will make the region more unstable," the ministry said in a statement.
"YPG/PKK terrorist organization that controls the region by force does not have the right and the authority to make a statement and invite other elements on behalf of people in the region," it added.
The ministry said it closely monitors the issue.
The statement came after the Syrian regime forces reportedly entered Manbij in coordination with the YPG/PKK terror group.
Assad regime forces on Friday entered the strategic northern city of Manbij, held by the YPG/PKK since recapturing the area from the Daesh terror group in 2016.
The YPG/PKK had said it invited regime troops "to assert control over the areas our forces have withdrawn from, particularly in Manbij, and to protect these areas against a Turkish military operation".
But Turkish President Recep Tayyip Erdoğan told reporters in Istanbul that there was "nothing certain there" in Manbij after he had discussions with intelligence officials.
He dismissed the regime's actions as an attempt to use "psychological" warfare.
In its more than 30-year terror campaign against Turkey, the PKK -- listed as a terrorist organization by Turkey, the U.S. and the EU -- has been responsible for the deaths of some 40,000 people, including women and children. The YPG is its Syrian branch.
