Fighting broke out north of Yemen's capital and in the centre of the country on Sunday, killing more than 20 people, hours before a truce was due to come into force to facilitate peace talks.
Yemen's Saudi-backed government and its Iranian-allied Houthi enemies were set to implement a UN-backed cessation of hostilities from midnight (2100 GMT) before talks to end the year-old war begin in Kuwait on April 18.
The United Nations hopes this will lead to a more concrete, formal ceasefire with confidence-building measures.
The war has killed more than 6,200 people, drawn in rival regional powers Saudi Arabia and Iran and triggered a humanitarian crisis in one of the Arab world's poorest countries.
In the capital Sanaa, controlled for the last 18 months by the Houthis, residents said they desperately wanted this attempt at peace to succeed after two rounds of talks failed last year.
"I am tired of the fighting, the destruction, everything," said Hussein Ali, a 57-year-old government employee.
"The situation is very difficult for people without work, without electricity, without water, and with the fear that, at any moment, bombardment could kill those dear to us."
But hours before the fighting was due to stop, heavy battles flared between forces loyal to President Abd-Rabbu Mansour Hadi and Houthi fighters in al-Maton, north of Sanaa, residents said.
In the central Bayda province, battles in the districts of al-Sawadiya and al-Zaher killed more than 20 people, local officials and residents said, and fighting continued in the southwestern city of Taiz.
"I hope that, when I wake up in the morning, the war has stopped," said 16-year-old student Amal Ahmed in Sanaa, "and I can go to school, my classmates too, without being afraid of raids and death."
Hadi, whose forces are backed by a Saudi-led military coalition that has been carrying out air strikes for the past year, met his advisers in Riyadh on Sunday, Yemeni officials said.
They said the Houthis had not yet informed the United Nations about their latest position on the agreement to stop fighting. A spokesman for the Houthis could not immediately be reached for comment.
