US President Donald Trump and his Secretary of State Rex Tillerson have sent mixed signals over a rift between Qatar and its regional neighbors.

Saudi Arabia, the UAE, Bahrain, Egypt, Libya, and several other countries cut off diplomatic ties with Qatar on Monday over allegations that Doha is sponsoring terrorism and destabilizing the region.

Qatar has vehemently denied the accusations, calling them unfounded.

On Friday, Trump accused Qatar of funding terrorism, calling on the small Persian Gulf country to stop supporting terrorist activities.

"The nation of Qatar, unfortunately, has historically been a funder of terrorism at a very high level," he said at a joint news conference with Romanian President Klaus Iohannis in Washington on Friday. "They have to end that funding."

His comments come shortly after Tillerson urged Saudi Arabia and its regional allies to ease their blockade of Qatar, saying it was causing unintended humanitarian consequences and affecting the so-called US-led fight against Daesh terrorists.

"We call on the kingdom of Saudi Arabia, the United Arab Emirates, Bahrain and Egypt to ease the blockade against Qatar," Tillerson said in a brief statement to reporters.

He said that the blockade was also causing food shortages, the forced separation of families and children being pulled out of school.

"Our expectation is that these countries will immediately take steps to de-escalate the situation and put forth a good faith effort to resolve their grievances they have with each other," Tillerson added.

Trump on Tuesday praised the move by the Arab states, but a day later offered to help resolve the worsening diplomatic crisis.

In a phone call with Qatari Emir Sheikh Tamim bin Hamad al-Thani, the US president said it was important for the regional countries to work together “to prevent the financing of terrorist organizations and stop the promotion of extremist ideology.”

Qatar was subsequently expelled from a Saudi-led coalition, which has been conducting a military aggression against Yemen since March 2015.

Qatar, home to the forward headquarters of the US military's Central Command and some 10,000 American troops, had assigned some of its US-provided fighter jets to the unprovoked war, which has killed over 12,000 Yemeni people while plunging the impoverished country into a humanitarian crisis.

Washington has been actively supporting the Saudi-led war, supplying weapons and intelligence to the aggressors under the guise of fighting terror.