A police officer was temporarily blinded by a laser shone into their eyes during a protest outside a hotel housing asylum seekers.
The constable had been driving a van when they were stunned near The Bell Hotel in Epping, Essex, on Sunday.
Ch Insp Terry Fisher, from Essex Police, said: “It is only testament to his professionalism that he safely kept control of the van and brought it to a stop.”
Two arrests were made throughout the demonstrations, during which some participants set off smoke bombs. They were a 27-year-old woman from Epping, who was arrested on suspicion of assault, and a man, 45, from Newham in east London, on suspicion of affray.