Police are stepping up patrols in central Manchester this weekend after a spate of violent disturbances, including an officer being attacked.
Greater Manchester Police said they will be paying particular attention to Piccadilly Gardens during coming days.
Four people were arrested on Thursday after allegedly becoming violent as a protest took place nearby.
An officer was allegedly headbutted and kicked in the mouth by one of the arrested men.
Police said up to 20 people, reportedly drunk and causing trouble, were seen fighting and throwing street furniture at a shop.
Later that evening, a further three women were arrested following a report of an assault on a homeless man.
Ch Insp Gareth Parkin said: "This is the second incident in just a few days where police have responded to reports of anti-social behaviour and criminality in Piccadilly Gardens.
"I want to make it clear that if anyone does go to Piccadilly Gardens or anyone else in our city centre, with the intent of causing trouble then we will not hesitate to make arrests."
