Turkey wants to ensure that the "wrong groups" do not take part in the operation to push Islamic State from the Syrian city of Raqqa and the offensive is weeks away from starting, Foreign Minister Mevlut Cavusoglu said on Tuesday.
Cavusoglu told a news conference that the United States had told Turkey that such groups - a reference to the Syrian Kurdish YPG militia - would only take part in the siege of Raqqa and not enter the city, Islamic State's de facto capital in Syria.
But he said Turkey was "taking measures" after its partners did not keep promises regarding the Syrian city of Manbij, from where Turkey has repeatedly said the YPG must withdraw.
Washington's support of the YPG has infuriated Ankara, which sees the group as an extension of the outlawed Kurdistan Workers Party (PKK) and worries that their advances in Syria will inflame a three-decade Kurdish insurgency in Turkey.