“Raqqa issue is not our problem,” Yildirim told reporters in the Turkish capital Ankara, specifying Turkish security forces were working for Turkish citizens' security.
The Syrian city Raqqa is the so-called capital of the ISIS terror group.
“We have a loud and clear stance there. We can be with you [the U.S.] against ISIS in the Raqqa operation but if elements such as PYD/YPG, which we identified as terrorist groups, join the operation, we are not there,” he said.
According to Turkey, PKK affiliates in Syria, namely the PYD and its military wing the YPG, are driving separatist motivations in northern Syria by creating cantons along the Turkish border.
The PKK and its Syrian offshoot the PYD are both listed as terrorist groups by Turkey although the U.S. and EU only view the PKK as a terrorist organization.
The Turkish PM said that fighting alongside "terrorists" -- especially the PKK -- against another terror group was not suitable for a constitutional state.
“We can never be together with those terror groups,” he said.
On Thursday, Erdogan discussed new potential routes for Operation Euphrates Shield in Syria as he spoke of the Free Syrian Army retaking, with the support of Turkey, Jarabulus, Al-Rai and Dabiq.
"There are almost 30,000 people in Jarabulus now; they moved back to their hometown," Erdogan said.
"Now we are on the way to Al-Bab because Al-Bab is an important headquarters for [ISIS]. They will leave Al-Bab and the campaign will go on. We will head to Manbij and Raqqa," he added.