The verdict, which is appealable, also includes the referral of five minors to a juvenile court, judicial sources said.
The charges relate to clashes between backers and opponents of ousted president Mohamed Morsi outside the Muslim Brotherhood's main headquarters in Moqattam district.
Eighteen people were arrested over the clashes, including seven guards of Brotherhood deputy leader Khairat al-Shater.
Prosecutors accused the defendants of assaulting a number of journalists and a female activist.