Almost 10,000 people have been killed in Yemen's conflict, in what the United Nations has called the world's humanitarian crisis.
UN envoy to Yemen Martin Griffiths says he will present a plan to the UN Security Council for resumption of peace talks between the warring parties in Yemen.
Griffiths, a former British diplomat who replaced Mauritania's Ould Cheikh Ahmed as the UN Special Envoy last month, briefed the UN Security Council for the first time on Tuesday.
Though mostly symbolic rather than effective, the use of drones and missiles by the Houthis allows them to generate worldwide headlines by threatening global shipping in one of the world's busiest trading arteries and raise the domestic costs of Riyadh's ongoing intervention in Yemen, which is now entering its fourth year.
Griffiths cited the firing of ballistic missiles against Saudi Arabia, intensified military operations in northwestern Saada governorate, ongoing air raids and movements of forces in the Hudaida region as worrisome developments.
Urgent and creative ways must be found "to diminish the chances of these game-changing events, upsetting and derailing the hopes of the great majority of Yemenis".
Yemen's UN Ambassador Khaled Hussein Mohamed Alyemany told reporters: "We don't have the intention to advance on Hodeidah".
Saudi Arabia's Foreign Minister Adel al-Jubeir has said that the success of any political solution in Yemen depends on the Houthi militias.
Iran has repeatedly denied arming the Huthis in Yemen, despite claims by the United States and Saudi Arabia that the evidence of an arms connection is irrefutable.
More than 9,200 people have been killed since the Saudi-led alliance joined the Yemen war, according to the World Health Organization.
The Yemeni Ministry of Human Rights announced in a statement on March 25 that the Saudi-led war had left 600,000 civilians dead and injured during the past three years.