The Muslim Brotherhood-led National Alliance to Support Legitimacy has called for mass protests on Friday under the banner of "Egypt against the coup."
Earlier on Wednesday, Egypt's cabinet issued a statement saying it would take "all legal measures necessary to confront acts of terrorism and road-blocking"  in an apparent warning to supporters of deposed Brotherhood president Mohamed Morsi, who have been camping out at two sit-ins in Cairo since the president's ouster on 3 July.
The pro-Morsi alliance responded with a statement read by a spokesman and aired on Al-Jazeeraon television calling for million-man protests on Friday.
"The alliance affirms that the Egyptian nation now recognises the true terrorists after several massacres committed by the putschists against pro-Morsi protestors," said the statement.
Over 80 pro-Morsi demonstrators were killed in violent clashes with police in the early hours of Saturday morning, a short distance away from the main sit-in in Nasr City.
Speaking about the interior ministry, which the cabinet statement charged with dispersing the protests, the alliance statement read: "Whatever they do, we will not be silent about their thugs…Let the world know who is peaceful and who is inciting terror."
The alliance backs continued peaceful protest until demands for Morsi's return are met.
"Our peacefulness will prove stronger than their bullets," said the spokesman.
In a plea to the United Nations, the Muslim Brotherhood-led coalition called on the international organisation to oppose the "coup" and condemn the mass killing of protestors.
The spokesman denied claims that protesters at the Nasr City demonstration are armed, and invited television channels to search for weapons at the sit-in.
The statement called for the constitutionally-guaranteed right to peaceful assembly to be upheld and appealed to the armed forces and police to refrain from directing bullets at "their Egyptian brothers."