A man has been bashed after asking a group of nearby partygoers to turn their music down, with a local councillor claiming locals fear for their safety.

The incident occurred on Friday night in Dee Why, on Sydney's Northern Beaches, and resulted in a 47-year-old being found by neighbours with severe injuries.

The man, who lives in a unit next to James Meehan Reserve, called out to a group partying in the park, asking them to turn their music down.

A nearby witness told Nine News the group had a 'boom box' which they described as 'really, really loud at one stage'.

Another witness said the victim was shouting at the group from his balcony before he went down to meet them.

It was then that he became surrounded and bashed, according to police, who said he was taken to hospital with facial injuries.

'He believes he was lying there for an hour but we're yet to investigate that properly,' Inspector Vanessa Robinson said.

He's in a stable condition, but the incident has left the local community anxious.

Local councillor Vincent De Luca told Nine News that Northern Beaches locals were living in fear in their own community.

'Locals are petrified to even take their dogs for a walk. We have an epidemic of gang crime and that must be addressed,' he said.

'NSW Police need to get onto this pretty quick, our community expect arrests and expect justice,' he said.

Nine News claimed locals told them that the incident was not surprising for the area and they were scared at times.

Inspector Robinson said that, despite the incident, it was safe to go to parks. 

Earlier this year, authorities urged parents to track their children on e-bikes amid a surge of unruly behaviour across Sydney, particularly the Northern Beaches.