Businesses near Yagan Square say violence and anti-social behaviour are becoming too common in the tourist hotspot after a 50-year-old man was allegedly coward-punched there on Saturday night.

CCTV footage shows the the man struck to the ground with police saying he hit his head on the concrete and was knocked unconscious during the attack

The victim was taken to hospital but discharged soon after.

The first officers to respond to the incident were part of Operation Night Safe, where extra police patrols are deployed to the party precinct every Friday and Saturday night to keep revellers safe.

But despite extra boots on the ground police figures show a 39 per cent increase in assaults in Northbridge last financial year.

Nearby businesses told 7NEWS they were too scared to talk about the crime on the record because they feared retaliation.

A 21-year-old will face court over the Saturday night attack later this month.