In the Saudi capital Riyadh, Gulf foreign ministers met to discuss the crisis in Yemen, after proposing an exit plan for Saleh.
Security forces were deployed heavily in Sanaa where hundreds of thousands of men and women took to the streets in protest at Saleh's call for an end to men and women demonstrating together against the regime and calling for his ouster.
But clashes soon erupted when security forces opened fire and shot tear gas grenades at protesters, wounding one and leaving 25 others suffering from breathing difficulties, according to medics at a field hospital there.
Security forces also used water cannon to disperse demonstrators as police cars carried away many wounded protesters, witnesses told AFP.
Protesters also took to the streets in the cities of Taez and Ibb, south of Sanaa, and the Red Sea city of Al-Hudaydah, the organisers said.
"We want to overthrow the regime and to bring the assailant to justice," read their banners.
The demonstrations came as foreign ministers of the oil-rich Gulf Arab monarchies met a delegation from the poverty-striken country's opposition in Riyadh.
The delegation, led by Mohammed Salem Bassandawa, himself a former foreign minister, and Yassin Saeed Noman, head of the opposition Common Forum, were in the Saudi capital seeking details on a plan for Saleh's departure.
"We will meet with the Gulf Cooperation Council ministers in Riyadh to ask for clarification on their initiative, especially on the departure of President Saleh," Noman said ahead of the talks.
Abdelwahab al-Ansi of the Islamist Al-Islah party, Sultan al-Atwani of the Unionist Nasserist Party, and Hassan Zaid of Al-Haq Zaidi party were also among the Yemeni delegation.
The GCC meeting was its third in two weeks on Yemen, Saudi state news agency SPA said.
The Common Forum, an alliance of the parliamentary opposition, has made the veteran strongman's departure a prerequisite for any political settlement, and the Gulf Cooperation Council's bid to resolve the crisis calls for him to hand over power to his vice-president.
Saleh's office has said in response to the mediation bid of the six-nation GCC that he has "no reservation about transferring power peacefully and smoothly within the framework of the constitution."
And on Friday, Saleh stood defiant as the elected president of the impoverished country when his supporters massed near the presidential palace.
"These popular masses, these millions, in this square have come to say 'yes' to constitutional legitimacy," Saleh told the crowd of tens of thousands.
More than 125 people are estimated to have been killed since protests calling for Saleh's ouster erupted in late January, inspired by uprisings which toppled long-time rulers in Tunisia and Egypt.