Human Rights Watch says rebel forces shot and killed two women and detained 10 local aid workers.
Saudi Arabia says a humanitarian ceasefire it has announced in Yemen will only take place if the Houthi rebels cease hostilities.
Adel al-Jubeir, the kingdom’s foreign minister, said the truce would begin on Tuesday and will last five days, but he warned air strikes would resume if the rebels failed to live to the “agreement”.
“The ceasefire will end should Houthis or their allies not live up to the agreement – this is a chance for the Houthis to show that they care about their people and they care about the Yemen people,” Jubeir told a joint news conference in Paris with US Secretary of State John Kerry.
Kerry said the ceasefire would take place “provided that the Houthis agree that there will be no bombing, no shooting, no movement of their troops or manoeuvring to reposition for military advantage [and] no movement of heavy weapons”.
He stressed that the pause in hostilities was a “renewable commitment” that, if it held, “opens the door to possibility of an extension”.
Kerry visited Saudi Arabia on Wednesday and met with Yemeni President Abd-Rabbu Mansour Hadi during a visit intended to push for a truce.
Hakim Almasmari, a journalist and analyst on Yemen, told Al Jazeera public opinion in the country was turning against the Houthis.
“There’s rising public anger against the Houthis in Yemen because Saudi Arabia has shown willingness that it wants a ceasefire…the Houthis have not responded to this call or shown any positive reaction,” he said.
Aid agencies have been struggling to deliver essential supplies to the victims of the fighting in Yemen, which began on March 26 when a coalition of Arab nations led by Saudi Arabia began bombing rebel positions.
The rebels swept into the Yemeni capital Sanaa in September and have since tried to expand their control across the country. In February, they stormed the presidential palace in Sanaa and put Hadi under house arrest before he fled to Saudi Arabia.
UNICEF has warned that fuel in Yemen may run out in less than a week, complaining that humanitarian access is being blocked by many parties to the conflict.
‘Red line’ crossed
Weeks of fighting have left more than 1,400 people dead and nearly 6,000 wounded, many of them civilians, forcing the United Nations to renew its plea for a ceasefire.
The fighting has spilled into Saudi Arabia, where rebels have killed civilians and Saudi soldiers, according to Saudi media.
The coalition on Friday said the rebels had crossed a “red line” by shelling populated border areas in the kingdom and ordered residents in Saada province bordering Saudi Arabia to leave, saying “all of Saada will be a military target”.
Witnesses in Saada cited by the AFP news agency said coalition jets dropped leaflets urging residents to leave
Coalition warplanes pressed ahead with air strikes on Friday, targeting rebel control centres, a communications complex, a landmine factory and other rebel positions across Saada, state media in Riyadh said.
Most of the fighting has been reported in the southern port city of Aden where Houthi rebels, battling forces loyal to the exiled president, continue to push for control of key towns despite six weeks of aerial bombardment by the coalition.