US Secretary of State Rex Tillerson on Tuesday called for an end to the more than seven-month dispute between a Saudi-led bloc and Qatar, warning it is harming regional security.
Saudi Arabia, Bahrain, the United Arab Emirates and Egypt broke off ties with Qatar in June last year, accusing it of supporting extremists and being too close to Iran.
Qatar denies the allegations and accuses the bloc of aiming to undermine its sovereignty.
Tillerson, in Kuwait for a meeting of the US-led coalition fighting the Islamic State group, said the United States was working to settle the Gulf dispute.
"This type of division is counterproductive to the security of the region," the top US diplomat said, speaking alongside his Kuwaiti counterpart at the meeting.
Qatar is home to the largest US airbase in the Middle East, Al-Udeid, which houses some 10,000 American troops and has been key in the war against IS.
He urged allies to stay focused on fighting the Islamic State group, saying Turkey's military offensive in northern Syria had "detracted" from the anti-militant battle.
Tillerson spoke at a ministerial meeting in Kuwait of the US-led military coalition that has been fighting IS in Iraq and Syria, being held in parallel with a conference on reconstruction in Iraq.
The militant group has lost much of the territory it once controlled when it seized large swathes of Syria and neighbouring Iraq in 2014.
"The end of major combat operations does not mean we have achieved the enduring defeat of ISIS," Tillerson said.
"ISIS remains a serious threat to the stability of the region, our homelands and other parts of the globe," he said.
Iraq declared victory over IS in December, but the extremist group still has a presence in Syria, where the US-led coalition has backed a Kurdish-Arab alliance fighting the jihadists.
And Iraqi government forces backed by a US-led coalition last week staged a major operation against "IS remnants" in the northeast.
The Turkish operation "has detracted from our fight to defeat Islamic State in eastern Syria", Tillerson said of ongoing offensives by US-backed Kurdish militia to clear remaining pockets of extremists.
"Forces have diverted from there to Afrin," he said.
The Kurdish People's Protection Units (YPG) have been a key component of the US-backed alliance fighting IS, but Washington's Nato ally Turkey says they are a "terrorist" offshoot of the outlawed Kurdistan Workers' Party (PKK).
"We remain concerned over recent events in northwest Syria and call on all parties to remain focused on defeating ISIS," Tillerson said.
"We will continue to be completely transparent with Turkey about our efforts in Syria to defeat ISIS," he added, giving a nod to Turkey's right to "counterterrorism efforts" on its border.
War-battered Iraq sought to attract international investors to rebuild the country at a parallel reconstruction conference in Kuwait, offering hundreds of projects and touting extensive legal guarantees.
"Iraq is open for investors," declared Sami al-Araji, chairman of Iraq's National Investment Commission, on the second day of the conference.
Baghdad says it needs nearly $90bn to rebuild devastated homes, schools, hospitals and economic infrastructure after three years of war against IS.