Prime Minister Binali Yildirim says Turkey will not allow cooperation with terrorist organizations in Syria, referring to Kurdish groups which the US supports.
Ankara and Washington have long been at loggerheads over the role of a US-backed Syrian Kurdish militia.
Turkey says the fighters are a terrorist organization affiliated with the outlawed Kurdistan Workers Party (PKK) but the US sees them as a partner in Syria operations.
In a speech to his ruling AK Party in parliament on Tuesday, Yildirim said Turkey won't allow formation of new states in Syria, echoing suspicion that the Kurdish campaign was aimed at establishing a separate state.
Turkey has been shelling the positions of Kurdish fighters in northern Syria.
Last month, Turkish President Recep Tayyip Erdogan angrily denounced US troops for wearing insignia of Syrian Kurdish People’s Protection Unit (YPG) during an operation in Syria.
In his Tuesday speech, Yildrim also said Turkey will never change its anti-terrorism laws, even if it would mean a collapse in a deal with the EU to secure visa-free travel for Turks to Europe.
Turkey and the EU have been discussing visa liberalization since 2013 and agreed in March to go ahead with it as part of a broader deal to halt refugees from Turkey to the EU.
But progress stalled when Brussels insisted that Ankara must also reform its tough anti-terror laws.
Ankara is under fire for its heavy-handed crackdown on the country’s Kurdish minority in the southeast.
Last month, Turkish Foreign Minister Mevlut Cavusoglu ruled out any potential alteration of the law.