Supporters of ousted president Mohamed Morsi began rallying across Egypt on Friday afternoon in response to a call by the Muslim Brotherhood's National Alliance to Support Legitimacy.
Thousands began marching from mosques after noon prayers in Cairo and several governorates, amid tightened security measures.
In Cairo, police have blocked areas around expected marching destinations. In Mohandessin, Central Security Forces (CSF) fired teargas and shots into the air to prevent protesters approaching Sphinx Square. A CSF officer warned that those breaking the cordon around the square would be arrested.
Outside the capital, protests were reported in the northern cities of Alexandria, Beheira, and Menoufiya, Upper Egypt's Assiut and the Delta's Gharbiya.
The National Alliance to Support Legitimacy released a statement on Wednesday saying that 30 August would be “the beginning of a civil disobedience campaign to pressure the putschists to end the coup.”
Egypt's interior ministry announced ahead of Friday's protests that it would use live ammunition against protesters in "legitimate self defence."
The statement comes amid an ongoing crackdown on the Muslim Brotherhood and its supporters after security forces forcibly dispersed two pro-Morsi protest camps in Cairo on 14 August, which left hundreds dead and over a thousand injured.
Since then, security forces have arrested hundreds of the group's leaders and members. Senior Brotherhood officials are facing incitement charges.
Police have also announced they will prevent the establishment of fresh sit-ins.
Morsi supporters have been demonstrating for almost two months against the army's overthrow of Mohamed Morsi on 3 July following mass protests against his rule.
The interim government has accused Morsi supporters of committing "terrorist acts" against its opponents.