Egypt will host the foreign ministers of Saudi Arabia, the United Arab Emirates and Bahrain on Wednesday to discuss the crisis with Qatar, Cairo's foreign ministry said.
The ministers will meet "to follow developments... concerning relations with Qatar," it said in a statement Sunday evening.
The four countries announced on June 5 they were severing ties with their Gulf neighbour, accusing it of backing "terrorism" and being too close to Saudi Arabia's arch-rival Iran.
Riyadh and its allies on Monday extended a deadline for Doha to accept 13 demands in return for lifting a de facto blockade.
Qatar has called the charges baseless and says the demands - including closing Qatar-based al Jazeera TV and ejecting Turkish troops based there - are so severe that they seem intended to be rejected.
Saudi Arabia, Bahrain, Egypt and the United Arab Emirates (UAE) have raised the possibility of further sanctions against Qatar if it does not comply with the 13 demands presented to Doha through Kuwait, which is acting as a mediator.
According to a joint statement on Saudi state news agency SPA, the four countries agreed to a request by Kuwait to extend by 48 hours Sunday's deadline for compliance.
They have not specified what further sanctions they could impose on Doha, but commercial bankers in the region believe that Saudi, Emirati and Bahraini banks might receive official guidance to pull deposits and interbank loans from Qatar.
Trump spoke separately to the leaders of Saudi Arabia, Qatar and the Crown Prince of Abu Dhabi in the UAE to discuss his "concerns about the ongoing dispute", the White House said.
"He reiterated the importance of stopping terrorist financing and discrediting extremist ideology. The president also underscored that unity in the region is critical to accomplishing the Riyadh Summit's goals of defeating terrorism and promoting regional stability," the White House said.
"President Trump, nevertheless, believes that the overriding objective of his initiative is the cessation of funding for terrorism," it said.
