Calls comes as country grapples with bloody conflict, cholera outbreak, lack of fuel, food and medicine
President Donald Trump has ordered U.S. officials to urge Saudi Arabia to completely allow fuel, food and medicine into Yemen.
In a short statement Wednesday, Trump said, "This must be done for humanitarian reasons immediately," saying the Yemeni people "desperately need it."
A Saudi-led coalition is carrying out an air and ground campaign to drive the Iranian-backed Houthi rebels out of Yemen.
The Saudis imposed a blockade on all Yemeni ports last month when the Houthis fired a missile near the Riyadh airport.
The blockade has been eased to allow some humanitarian aid into the country, but the Saudis have tightened restrictions on commercial shipping, causing severe fuel shortages.
No fuel means generators that pump clean drinking water, run hospitals and cook food cannot operate.
Saudi Arabia is one of the closest U.S. allies in the Arab world, but it is unclear exactly what approach U.S. officials and diplomats will take in persuading the Saudis to ease the blockade.
Saudi Foreign Minister Adel al-Jubeir told Reuters last month that no country has given more aid to Yemen than Saudi Arabia. But he said none has gone to Houthi-controlled areas of northern Yemen, accusing the rebels of stealing and selling the aid.
The Houthis seized the Yemeni capital of Sana’a in 2014, forcing the internationally recognized government of President Abd-Rabbu Mansour Hadi to flee to Saudi Arabia before returning to the southern port of Aden.
The Saudi airstrikes aimed at forcing out the Houthis have obliterated entire neighborhoods and killed thousands of civilians.
Yemen is also struggling with a cholera outbreak and what the U.N. is warning is a looming famine.
