The United Nations has announced that it will sponsor "inclusive" talks on the conflict in Yemen next week.
Secretary General Ban Ki-moon said he hoped the consultations in Geneva would "restore momentum towards a Yemeni-led political transition process".
But the foreign minister for the exiled government said it might not attend because it wanted more time to prepare.
A Saudi-led coalition resumed bombing Houthi rebels and their allies after a five-day ceasefire ended on Sunday.
Overnight, warplanes targeted army bases and weapons depots in the most sustained bombardment of the capital, Sanaa, in almost two months, residents said.
The UN says at least 1,850 people have been killed and more than 7,390 injured in air strikes, fighting on the ground and attacks by militants since 19 March.
More than 500,000 Yemenis have also been displaced from their homes, and millions have been affected by shortages of food, water, fuel and medicines.
Mr Ban urged all parties to the conflict to engage in the talks, which will begin on 28 May, "in good faith and without preconditions", his spokesman said.
"The only durable resolution to the crisis in Yemen is an inclusive, negotiated political settlement," Mr Ban warned.
The announcement follows extensive consultations by the UN's special envoy, Ismail Ould Cheikh Ahmed, together with expressions of support by the UN Security Council.
The Security Council has called for the restoration of Yemen's President Abdrabbuh Mansour Hadi, who fled the country in March, and the resumption of the democratic transition begun in 2011 when former leader Ali Abdullah Saleh was forced to hand over power following mass protests.
Yemen's Foreign Minister Riad Yassin expressed surprise at Mr Ban's talks announcement.
"We didn't get an official invitation," he told the Reuters news agency. "It's very short notice. If it happens, it shouldn't be on 28 May."
Mr Yassin added that the Houthis should be required to disarm and leave the cities they have seized since September before being allowed to attend.
The government organised a three-day conference on Yemen's future that concluded in Saudi Arabia on Tuesday.
It was attended by hundreds of Yemeni politicians and tribal leaders, but the Houthis refused to participate. They rejected the main aim of the conference - the restoration of Mr Hadi - and the decision to hold it in a country leading the air campaign against them.
During the five-day ceasefire that ended on Sunday, international humanitarian organisations scrambled to get desperately-needed aid to the hardest-hit areas of the country.
On Wednesday, Iran's deputy foreign minister announced that an Iranian cargo ship carrying 2,500 tonnes of aid would now submit to inspections at the UN's hub in Djibouti before sailing on to Yemen's Red Sea port of Hudaydah.
Iran had refused to allow Saudi-led naval forces to carry out an inspection of the vessel to ensure it was not transporting arms supplies for the Houthis.