A silent disco caused residents sleepless nights from shouting and left people upset that police did not step in to stop it.
More than 100 people had gathered in a park in Bristol for at the weekend for the gathering where people listened to music on headphones.
But extra sounds, such as a generator, had caused "sleeplessness and anxiety".
Avon and Somerset Police said it was "aware" of concerns and was targeting events that broke Covid rules.
Resident Ted Fowler said residents were fearful of confronting the organisers at Owen Square Park in Easton.
"Every time there's been contact with the police and there's been no response."
Penny Gray said people had been finding glass and excrement in the park.
"I have a lot of respect for the police, but it is not a priority or are they not resourced enough to prevent them from happening?"
Councillor Afzal Shah said he too was disappointed by the police's response.
He said the "illegal parties" some involving big sound systems had been taking place for at least the past six weeks and "should have been nipped in the bud".
Avon and Somerset police said it was "fully aware" of concerns from local residents about gatherings and anti-social behaviour in Owen Square Park.
Insp Deepak Kenth said he was hearing residents' concerns "loud and clear".
"I would encourage them to report what's happening so we have a better picture and can take the appropriate action," he added.