A day earlier, police stormed a Cairo mosque where Morsi loyalists had holed up, after trading fire with gunmen inside its minaret.
The call for fresh demonstrations looked set to test the so-called Anti-Coup Alliance of Morsi loyalists, which failed to hold mass rallies on Saturday, but has insisted that protests will continue.
The group announced two major rallies in east and south Cairo following afternoon prayers at 1400 GMT.
Ahead of the rallies, some semblance of normality returned to the streets of the capital, which is under a night-time curfew and has been unusually quiet in recent days.
Traffic was almost at normal levels, and banks and shops opened their doors cautiously after four days of violence since Wednesday, when police cleared two pro-Morsi protest camps.
At least 578 people died across the country in clashes following the operation, and the government said another 173 people were killed between Friday and Saturday, bringing the toll in just four days to more than 750.
The violence has shocked the international community, but Egypt’s government – installed by the army after Morsi’s July 3 ouster – has fiercely defended its actions.
Egypt has found itself divided as never before in recent history, with Morsi’s many opponents stridently condemning his supporters as “terrorists.”
On Saturday, as police dragged protesters from the Fath mosque in Cairo, angry bystanders tried to assault them, cheering as they were packed into police cars.
The area had turned briefly into a battleground, with security forces trading fire with gunmen inside the mosque, leaving bullet holes in its minaret.
The interior ministry said 385 people inside the mosque had been arrested.
There was renewed speculation that the government would move to ban Morsi’s Muslim Brotherhood, although the military-installed interim presidency appeared to dismiss the idea.
“We’re not into the effort of dissolving anyone or preventing anyone” from taking part in politics, presidential adviser Mustafa Hegazy insisted on Saturday.
According to an AFP tally, more than 1,000 people have been killed since mass demonstrations against Morsi at the end of June, among them a son of the Brotherhood’s supreme guide on Friday.