The health ministry spokesman said death toll from nationwide violence in Egypt has climbed to 638, making it the bloodiest day since the Arab Spring in 2011 toppled longtime President Hosni Mubarak in a popular uprising.
In Cairo, the march set out from the Al-Iman mosque, where dozens of corpses of protesters clad in white shrouds were lined up before grieving relatives.
Hundreds of Morsi supporters attacked the local government offices in Giza and set them ablaze. Television footage showed the headquarters in flames as men tried to douse the fire with hoses. Assailants used Molotov bombs to burn down the building, Al Arabiya reported.
There were also reports of clashes in Ma'adi, a neighbourhood in southern Cairo, between local residents and Morsi supporters, with witnesses saying both sides exchanged gunfire.
Muslim Brotherhood and anti-Morsi supporters Tamarod urged nationwide rival rallies tomorrow, setting stage for fresh confrontation.
"To every free Egyptian man and woman: Come out against the bloody military coup," Muslim Brotherhood and allies grouped in the National Alliance for Legitimacy said in a statement, predicting millions would take to the streets.
Tamarod (Rebellion) movement, which launched the June 30 protest that led to the ouster of Morsi, urged all Egyptians to take to the streets tomorrow to defend the country from "terrorism".
"During these difficult times, we must all stand together... To defend the future of our children from terrorism and the dark forces which want to drag us back centuries," the group said.
Tamarod called on "the great people of Egypt to form popular committees on all streets, outside homes and churches around the country, carrying Egyptian flags to reject domestic terrorism and foreign interference," the group said.
The military issued a stern warning against violence and interim President Adly Mansour said he would protect the country against those seeking "chaos" in his first address to the nation.
The military statement said that "whoever resorts to violence and deviates from peacefulness in Friday's rallies will put his life in danger".
After the attack on Giza governorates, the interior ministry has instructed "all forces to use live ammunition to counter any attacks on government buildings or forces.