The April 6 Youth Movement has called for a protest on Friday in Tahrir Square to express solidarity with the victims of recent sectarian clashes in Imbaba.
Twelve people died and 240 were injured in fighting between Muslims and Christians on Saturday in the poor, densely-populated district.
The clashes broke out after rumors circulated that a woman who had converted to Islam was being detained in a church.
The movement called for renouncing religious intolerance and tracking down people associated with former President Hosni Mubarak's regime, whom the military blamed for the violence.
The group condemned what it called "shameful delinquency" by military and security forces in handling the situation, adding that enforcing the law is the only means to solve any dispute.
