They were given prison sentences of between 30 and 42 months for rioting in the area between Western Street and Queen Street on July 28, 2019.
Two of them were also found guilty of assaulting a police officer and possessing a radio apparatus without a valid license.
In sentencing the defendants, Judge Johnny Chan said people cannot resort to violence even when peaceful means could not fulfill their goals.
The judge pointed out that there were a large number of protesters and that the case was serious.
He also noted that protesters were prepared with bricks, iron rods and laser pointers and that the riot had posed a serious danger to society.