Secretary of State John Kerry said on Friday the United States found a comment by Turkey's prime minister, likening Zionism to crimes against humanity, "objectionable", overshadowing their talks on the crisis in neighboring Syria.
Kerry, on his first trip to a Muslim nation since taking office, is meeting Turkish leaders for talks meant to focus on Syria's civil war and bilateral interests from energy security to counter-terrorism.
But the comment by Turkish Prime Minister Tayyip Erdogan at a U.N. meeting in Vienna this week, condemned by his Israeli counterpart, the White House and U.N. Secretary-General Ban Ki-moon, has clouded his trip.
"We not only disagree with it, we found it objectionable," Kerry told a news conference with Turkish Foreign Minister Ahmet Davutoglu, saying he raised the issue directly with Davutoglu and would do so with Erdogan.
"That said, Turkey and Israel are both vital allies of the United States and we want to see them work together in order to be able to go beyond the rhetoric and begin to take concrete steps to change this relationship," Kerry added.
Washington needs all the allies it can get as it navigates the political currents of the Middle East, and sees Turkey as the key player in supporting Syria's opposition and planning for the era after President Bashar al-Assad.
But the collapse of Ankara's ties with Israel have undermined U.S. hopes that Turkey could play a role as a broker in the broader region.
Erdogan told the U.N. Alliance of Civilizations meeting in Vienna on Wednesday: "Just as with Zionism, anti-Semitism and fascism, it has become necessary to view Islamophobia as a crime against humanity."
Erdogan's caustic rhetoric on Israel has in the past won applause from conservative supporters at home but raised increasing concern among Western allies.
Ties between Israel and mostly Muslim Turkey have been frosty since 2010, when Israeli marines killed nine Turks in fighting aboard a Palestinian aid ship that tried to breach Israel's blockade of the Gaza Strip.
"If Israel wants to hear positive statements from Turkey it needs to reconsider its attitude both towards us and towards the West Bank," Davutoglu told the news conference.
Writing by Nick Tattersall; Editing by Michael Roddy