The attacked were demonstrating for victims of the recent Maspero clash Hundreds of Coptic Christians marching in Cairo on Thursday came under attack by assailants throwing stones and bottles and 25 people were lightly injured in subsequent clashes, a security official said.
They were marching to demand justice for the Christian victims of a clash with soldiers in October that left at least 25 people dead, most of them Christians.
The official said the Copts were attacked in the northern Shoubra neighbourhood with stones and bottles, and that some among them responded in kind.
He said supporters of an Islamist candidate for upcoming parliamentary election joined in the attack on the Copts.
An AFP correspondent on the scene said hundreds of riot police were deployed to the area and that the clashes had eventually subsided.
Copts, who make up roughly 10 percent of Egypt's 80 million people, complain of discrimination in the Muslim-majority country.
There has been a spike in sectarian clashes since a popular uprising ousted president Hosni Mubarak in February.
The deadliest took place on October 9, when thousands of Christians protesting an attack on a church clashed with soldiers.
Witnesses said the soldiers fired on the demonstrators and ran them over with military vehicles, which the military denies.
The military said a number its soldiers were killed in the clash.