Mark Lowcock, the head of the UN's office for the Coordination of Humanitarian Affairs, said the consequences of the suspension of operations at the port of Hudeida would be "catastrophic". "It is essential for him to be given the time that he needs to facilitate a negotiated solution that avoids conflict in the city and we support his efforts to do so". One proposal is for the United Nations to take control of the port or the city.
The Red Sea port is a lifeline for eight million Yemenis, handling most of the country's commercial imports and aid supplies.
U.N. Yemen mediator Martin Griffiths has been holding talks with the Houthis to hand over control of the port to the United Nations, Yemeni political sources have said.
He said "90 percent of food, fuel and medicines in Yemen are imported" - and 70 percent come through Hodeida, including desperately needed humanitarian aid for over 7 million people.
He accused the Houthis of seeking to destabilize Saudi Arabia and threaten regional and global security, stating that firing ballistic missiles at residential areas was a violation of worldwide Humanitarian Law.
The U.S., he said, is closely following developments in Hodeidah and urged Emirati leaders to preserve "the free flow of humanitarian aid and life-saving commercial imports".
British UN ambassador Karen Pierce said London recognises the UAE's "security concerns".
"But we are also anxious about the humanitarian situation".
Yemen's Defense Ministry declared Monday that 250 fighters of the Shiite Houthi group were killed in battles with government forces in the country's western coast areas.
Urgent British-led efforts at the UN were under way to dissuade the United Arab Emirates and the Saudis from pressing ahead with the attack - or at least to give undertakings that it will not seek to starve Hodeidah into submission.
"If an attack does take place, casualties on all sides will be high, with a likely catastrophic impact on the civilian population", they wrote in a letter to the foreign secretary.
The coalition has been battling the Iran-allied rebels since March 2015, in a war that has killed more than 10,000 people. It has damaged Yemen's infrastructure, crippled its health system and pushed the Arab world's poorest country to the brink of starvation.