Hundreds of Islamists flocked to Rabaa al-Adaweya Mosque in Nasr City on Friday to join rallies supporting President Mohamed Morsy and condemning political violence.
However, the huge demonstration has developed against the backdrop of claims from media organisations that they have faced physical assaults.
The rally, dubbed "No violence…Yes to peaceful protests," was arranged by several Islamist groups, including the Muslim Brotherhood and its political wing, the Freedom and Justice Party (FJP).
Islamist youth groups monitored traffic flow in the streets surrounding the mosque ahead of Friday prayers. Street vendors sold their wares not far from the main platform for the protests.
The Muslim Brotherhood is reportedly expecting over 30 Islamist groups and parties to join the event.
The FJP's youth secretary, Ayman Abdel Ghany, said Thursday that all protesters would congregates outside the Rabaa al-Adaweya Mosque at 3 pm on Friday after prayers.
"The mass demonstrations call for the peaceful expression of opinion, renouncing violence and aim to uncover those who want to drag the country into a vortex of violence and chaos," Abdel Ghany posted on his Facebook page.
Abdel Ghany added that Islamists would not take part in violence, thereby giving their detractors an opportunity to cause bloodshed and destroy the country.
This tactic would also give the security services the chance to handle thugs infilitrating peaceful protests, the FJP official claimed.
However, BBC Arabic reported that its team covering the "no violence" protest had been assaulted Friday afternoon.
BBC Arabic reported that pro-Morsy protesters insulted members of its team and targeted its staff with empty water bottles. The protesters reportedly accused “corrupt media” of trying to undermine the “Islamic project.”
Dozens topped the broadcasting van and tried to assault the team, BBC Arabic said, adding that the team withdrew from the area, unable to continue its work safely.
Privately-owned Egyptian broadcaster OnTV also reported coming under attack from marchers armed with "sticks and rods." Assailants also smashed the TV crew's cameras.
Earlier OnTV Live broadcast images of Islamist marchers apparently practising martial arts away from the crowds.
The latest Islamist call for non-violence runs counter to statements made by some radical preachers over the past week, in which clerics promoted the use of violence against opposition demonstrations against President Mohamed Morsy planned for 30 June.
Radical Islamist preacher Wagdy Ghoneim said Friday that protests demanding the downfall of President Morsy represented a war between Islam and its “enemies."
Speaking in a YouTube video on his own channel, Ghoneim claimed that anyone rallying for the president's ouster is "an infidel and should be killed."
"Islam urged us to obey our rulers," he added. "Our president is an elected and legitimate one."
Edited translation from MENA