Bob Corker, the chairman of the Senate foreign relations committee, warned that efforts to fight so-called Islamic State and counter Iran were being hurt.
Saudi Arabia, the United Arab Emirates, Bahrain and Egypt cut air, sea and land links with Qatar three weeks ago.
They accused Qatar of aiding terrorist groups and Iran - charges it denied.
On Friday, the emirate was presented with a 13-point list of demands to end the crisis that included shutting down the Al Jazeera news network, cutting ties to the Muslim Brotherhood, and curbing diplomatic relations with Iran.
View of departures area at Hamad International airport in Doha, Qatar (20 June 2017)