Saad Hariri, Lebanon's prime minister, has called on the United States to help solve the dispute between Qatar and the four Arab states that have imposed a blockade on Qatar.

Saudi Arabia, Bahrain, UAE and Egypt cut diplomatic and transport ties with Qatar on June 5, accusing it of supporting "terrorism". Qatar rejects the allegations as "baseless".

"We believe that dialogue is the best way [for] improving the relationship between Saudi Arabia and Qatar," Hariri said during a joint press conference with US President Donald Trump on Tuesday.

"I believe that maybe the United States also could help in solving this issue in the Gulf."

Hariri said that he believes the Kuwaitis, who are mediating in the crisis, "have made some progress".

The US and UK have urged the Saudi-led groups to end the blockade.

Separately on Tuesday, Khalid bin Mohammed al-Attiyah, Qatar defence minister, said the blockade imposed on his country must be lifted before Qatar could engage in dialogue.

READ MORE: Get all the latest updates on the Qatar-Gulf crisis

On Friday, Qatari Emir Sheikh Tamim bin Hamad Al Thani said his country is ready for dialogue to resolve the crisis, but stressed that any solution must respect Qatar's sovereignty.

"We are open to dialogue to resolve the outstanding problems [so long as Qatar's] sovereignty is respected," Al Thani said in his first televised address on since the four Arab states cut ties with Qatar.

Hariri and Trump also discussed Lebanon's efforts to protect its borders against Islamic State of Iraq and the Levant (ISIL, known as ISIS) fighters and other armed groups.

Trump called the Lebanese Shia armed group, Hezbollah, a threat to the entire Middle East.

He added that he was not a "fan" of Syrian President Bashar al-Assad and pledged to prevent his government from carrying out any more chemical attacks.