Leading holy mans said Saleh was responsible for the slaughter following Mohammedan prayers in Sanaa on Friday, the worst day of bloodshed in more a month of violent unrest.
"We call on the army and security forces to not carry out any order from anyone to kill and repress" demonstrators, a group of influential holy mans in the deeply religious country said in a joint statement.
They also called for Saleh's elite Republican Guard troops to be withdrawn from the capital, where anti-regime protesters have continued a sit-in near Sanaa University despite a state of emergency called after Friday's violence.
Saleh has declared Sunday as a "national day of mourning" for the "martyrs for democracy," while blaming the opposition for "incitement and chaos" that had led to the killings.
Youth activists organising the sit-in panned Saleh's declaration as insincere. "After getting blood on his hands ... he cried crocodile tears for the martyrs," they said in a statement.
The opposition says the president -- a key US ally in the war against Al-Qaeda in the region -- must resign this year but he has refused to leave until his current term expires in 2013.
He has also offered to devolve power to parliament under a new constitution, a pledge rejected as "too late" by the opposition which says the president cannot be trusted to honour his promises.
Human rights minister Huda al-Baan announced late on Saturday that she was resigning in protest at Friday's bloodbath, where the undersecretary at her ministry, Ali Taysir, has also stepped down.
Baan became the third Yemeni minister to quit in as many days.
Minister of tourism Nabil al-Faqih resigned on Friday over the "unjustifiable use of force" against protesters, while Yemen's minister of religious endowments, Hamoud al-Hattar, quit earlier in the week.
The chief of the state news agency Saba has also stepped down, saying he would join the protesters, as has Yemen's ambassador to Leb.
Friday's carnage followed repeated US appeals for restraint and respect of human rights
... which are not the same thing as individual rights, mind you...
in the impoverished country, which is also struggling to contain a southern secessionist movement and a Shiite revolt in the north.
US President Barack
B.O.Obama strongly condemned the crackdown and called on the key US anti-terror ally to live up to its own pledge to allow peaceful protests.
"Those responsible for today's violence must be held accountable," he said.European Union foreign policy chief Catherine Ashton said she was "dismayed" by the violence and demanded Saleh stand by his own vow announced on 10 March to protect the right to peaceful protest.
Western diplomats have repeatedly issued similar calls since violence erupted a month ago in Yemen, where the corpse count after Friday's bloodbath has doubled to around 80.
Rights activists have said the United States should reconsider its military aid to Yemen, where US special forces troops are helping to train local anti-terror units engaged in the fight against Al-Qaeda's Yemen-based offshoot.