At least 11 people were killed on the first day of the UN-brokered ceasefire, despite all parties insisting they will pause the fighting.
The truce, for an initial period of three days, took effect shortly before midnight yesterday to allow sorely needed aid deliveries.
A Saudi-led Arab coalition intervened in March 2015 to support the government of President Abedrabbo Mansour Hadi after Huthi rebels overran much of the impoverished country on the southern tip of the Arabian Peninsula.
The coalition and Hadi both vowed to abide by the ceasefire despite alleged violations by the rebels.
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Pro-government forces declared "respect for the truce" but reserved the right to respond to infractions.
The rebels said they would respect the ceasefire as long as "the enemy" abides by it, but urged their fighters to be ready to retaliate against "all aggression."
The coalition has said it will continue an air and maritime embargo, to prevent weapons shipments to the rebels, and will maintain airborne reconnaissance.
"They're mocking us with a three-day truce," said Ali al-Doush, a 32-year-old civil servant who has not been paid for three months.
"We want an end to the war."
Nearly 6,900 people have been killed -- more than half of them civilians -- in the conflict, while another three million are displaced and millions more need food aid.
The deaths today included three civilians killed in a coalition air raid on Saada province, a historic Huthi stronghold, according to rebel-controlled media.
A man and his daughter were also wounded in a cross-border attack from Yemen on the kingdom's Jazan region, according to Saudi civil defence authorities.
Military sources and residents said there had also been fighting around besieged third city Taez, and pro-Hadi positions came under fire in Sarwah, east of Sanaa.