Egypt's Ministry of Interior says security forces observed infringements and excesses that fall beyond the realm of peacefulness in Friday's protests, which were held by supporters of deposed president Mohamed Morsi and critics of the armed forces.
"Many crimes were committed … blocking roads, disturbing traffic, assaulting several mosque preachers, abducting correspondents and stealing their equipment, and threatening the security of citizens," the ministry said in a statement published on its official Facebook page.
The interior ministry stressed that the police would "strictly face such practices" in the future in order to maintain security.
Security forces arrested Friday a number of Muslim Brotherhood supporters in several Egyptian cities following clashes between the Islamist group's supporters and opponents, state news agency MENA reported.
The confrontations left two dead in Alexandria and Beni Suef.
In Alexandria, Egypt's second largest city, army vehicles were deployed in several districts after Brotherhood supporters were chased by local residents near Al-Qaed Ibrahim Mosque, which has been a flashpoint for demonstrations since the 2011 January uprising.
Clashes also erupted in Alexandria's Corniche seafront road, prompting police to fire tear gas. MENA said a number of "rioters" were arrested in the city shortly afterwards.
The agency also said "a large number" of Brotherhood supporters were apprehended in the Nile Delta city of Mansoura after clashes broke out between protestors and locals, which left several injured.
There were similar skirmishes in the northern province of Sharqiya, where ousted president Mohamed Morsi was born.
Protest marches were called by the Muslim Brotherhood for Friday and Saturday in Cairo and other cities to mark the one-month anniversary of the violent dispersal by the police of two pro-Morsi sit-ins at Rabaa Al-Adawiya and Al-Nahda squares that left 600 dead and more than 40 officers killed.