Artillery and machine-gun exchanges rocked the southern part of Hudaydah in early morning before tapering off later in day, an AFP correspondent said.
The port city, which is a lifeline for the delivery of desperately needed humanitarian aid, was for months the main front line in the Saudi-led war on Yemen.
But last month the warring parties agreed a ceasefire for Hudaydah during UN-sponsored talks in Sweden.
The United Nations has said the truce has largely held since it came into force on Dec. 18 but there have been delays in the agreed pullback of both sides.
The Houthis control most of Hudaydah while the militants are deployed on its southern and eastern outskirts.
The Saudi aggression has killed thousands of people and unleashed the world's worst humanitarian crisis, according to the United Nations.
UN aid officials say 80 percent of the population - 24 million people - are in need of aid and nearly 10 million are just one step away from famine.