At least six people were killed on Friday in clashes between pro-Muslim Brotherhood protesters and the Egyptian police in Cairo, the health ministry said.
Supporters of ousted Islamist president Mohamed Morsi had held small marches after the morning prayers for Eid al-Fitr, which marks the end of the holy Muslim fasting month of Ramzan.
Police officials said the protesters attacked security forces stationed in Cairo's Talbiya district near the Giza pyramids.
The health ministry did not give a breakdown of those killed in the clashes.
Pro-Morsi protests have dwindled since his ouster by the military in 2013, which led to a massive crackdown on supporters, killing at least 1,400 people in street violence.
Hardcore supporters continue to hold small protests that are often confined to one or two Cairo neighbourhoods.
Demonstrations have largely given way to militant attacks, often resulting in small bombings and attacks on infrastructure such as electricity towers.
In the Sinai Peninsula, jihadists affiliated to the Islamic State group have killed hundreds of policemen and soldiers in an insurgency since Morsi's overthrow.
Morsi's Muslim Brotherhood has been blacklisted and thousands of its sympathisers have been jailed.
Hundreds, including Morsi, have been sentenced to death. Most have appealed the verdicts and won retrials.