US Secretary of State Antony Blinken told his Turkish counterpart Mevlut Cavusoglu on Monday that "PKK terrorists" bore responsibility for the deaths of Turkish hostages in northern Iraq.
Turkey had accused the United States of supporting "terrorists" after Washington declined to immediately back Ankara's claim that Kurdish militants had executed 13 Turkish nationals in Iraq.
"The Secretary expressed condolences for the deaths of Turkish hostages in northern Iraq and affirmed our view that PKK terrorists bear responsibility," State Department spokesman Ned Price said.
The Turkish anger had been directed at a US State Department statement on Sunday saying Washington "deplores the death of Turkish citizens" but awaited further confirmation of Ankara's version of events.
Turkish President Recep Tayyip Erdogan branded Washington's response "a farce" and the Turkish foreign ministry summoned US Ambassador David Satterfield to convey Ankara's displeasure "in the strongest possible terms".
Mr Price said Mr Blinken spoke by phone with Mr Cavusoglu on Monday and "emphasised the longstanding importance of the US-Turkish bilateral relationship" and "our shared interest in countering terrorism".
The PKK has been waging an insurgency against the Turkish state since 1984 that is believed to have left tens of thousands dead.
The US and Turkey's other Western allies consider the PKK a terror group.
But Washington has supported another Kurdish militia in Syria that Turkey sees as an offshoot of the PKK.
Turkey this month launched a military operation against rear PKK bases in northern Iraq.
Mr Erdogan said on Monday that this offensive was designed in part to free the 13 hostages.
Turkey's interior ministry also announced Monday that 718 people have been detained over alleged Kurdish militant links.
Mr Erdogan said Turkey's Nato allies had to pick sides.
"After this, there are two options. Either act with Turkey with no ifs or buts, without questioning, or they will be a partner to every murder and bloodshed," he said.
"The terrorist organisation on our doorstep, on our borders, is killing innocents."
