The anti-government white masks filed the complaint after red-shirt supporters assaulted and beat up a white-mask group in Chiang Mai on June 14.
White-mask demonstrators had assembled at Health Park behind Chiang Mai University, while some 200 red shirts gathered at the Grand Waroros Hotel before moving to attack the white masks.
In a letter, the group called on the National Human Rights Commission to investigate the red-shirt group and the red community radio “Rak Chiang Mai 51”, which they said incited people to attack the white masks.
They said police had not tried to stop the red shirts from attacking the white-mask demonstrators.