President Donald Trump spoke with Saudi Arabia’s King Salman on Thursday to discuss the dispute with neighbouring Qatar.
“The two leaders discussed regional security and key bilateral issues,” White House spokesman Judd Deere said.
“President Trump thanked King Salman for his leadership and expressed his optimism towards resolving the Gulf rift.”
Saudi Arabia, the UAE, Bahrain and Egypt cut ties with Qatar in 2017 because of Doha’s support for extremists, its ties to Iran and its interference in the internal affairs of its neighbours.
Mr Trump’s departing administration hopes to resolve the dispute before the president leaves office on January 20.
The call between Mr Trump and King Salman comes as senior American officials travel to the region in the final weeks of the administration.
Treasury Secretary Steve Mnuchin is expected to embark on a regional tour in the first week of January, which will include stops in the UAE and Qatar, Bloomberg News reported on Wednesday.
And senior White House adviser Jared Kushner travelled to Saudi Arabia and Qatar last month to try to resolve the dispute.
The Trump administration’s former Iran policy co-ordinator, Brian Hook, accompanied Mr Kushner.
The GCC’s annual summit is typically held in December, although Qatari Emir Sheikh Tamim has not attended the event since the boycott began.