Opponents of Egyptian President Mohammed Morsi are expected to hold new protests, after the deadliest week of violence since he came to power.
More than 60 people have been killed in the unrest.
On Thursday leaders of some of the main political factions signed an agreement condemning the violence.
But youth groups later called for more rallies. They plan to gather in Tahrir Square in Cairo after Friday prayers and march on the presidential palace.
The planned protests coincide with the first anniversary of football riots in Port Said, in which 74 people were killed.
Port Said has seen the worst of the violence over the past week, in clashes sparked by death sentences imposed on 21 local people in connection with the football riots.
Human rights officials, meanwhile, have expressed alarm over a rise in sexual violence against women in Cairo.
According to the UN’s Office of the High Commissioner for Human Rights, 25 women have been sexually assaulted, mainly in Tahrir Square, since the protests erupted.
Michelle Bachelet, of the UN’s Entity for Gender Equality and the Empowerment of Women, said she was “deeply disturbed by the gravity of [the] recent attacks”.
Sexual assaults against women around Tahrir Square was widely reported during the uprising there which eventually unseated Hosni Mubarak.
‘Collapse of state’
The current unrest began on 24 January in Cairo on the eve of the second anniversary of the 2011 revolution and has spread to several cities.
Protesters accuse Mr Morsi of imposing a new form of authoritarianism and betraying the values of their uprising two years ago.
Supporters of Mr Morsi say the opposition is trying to use the power of the street to unseat Egypt’s first democratically elected leader.
On Tuesday, Egyptian army chief Gen Abdul Fattah al-Sisi warned that the political crisis could lead to the collapse of the state.
Thursday’s meeting at the al-Azhar mosque was attended by President Morsi’s Muslim Brotherhood and by opposition figures.
The document signed by the leaders refers to the “sanctity of [citizens’] blood and of public and private property”, according to a text published by the Egyptian al-Ahram newspaper.
It says those signing “condemn the inciting of violence, its justification… and its exploitation in any form”.
Opposition politician Mohamed ElBaradei said he was optimistic after the meeting, saying differences should be solved peacefully.
Earlier this week, the National Salvation Front, formed by Mr ElBaradei, leftist Hamdeen Sabahi and former Foreign Minister Amr Moussa, turned down an invitation to talks with Mr Morsi.
They said they first wanted him to commit to the idea of a national unity government and a body to look at amendments to the new Egyptian constitution.
