It came as opposition council-lors tried to push through a ban on street drinking in Camberwell.
The area has been plagued with intimidating groups of drunks for decades.
Residents say their streets are used as open lavatories, while mothers and pensioners are afraid to use Camberwell Green.
Defending the borough-wide proposal, council leader Nick Stanton said emerging problem areas like London Bridge would also benefit.
He argued a specific ban for Camberwell would simply drive drunks elsewhere.
He said: "We don't want to be sitting here in six months saying, 'Camberwell's okay, now we have a problem in Walworth and Peckham'."
But Tory deputy leader David Bradbury said the proposed move was "illiberal", adding: "It's taking a sledgehammer to what in Camberwell is a nut."
Labour councillor Ian Wingfield, who suggested the Camberwell ban, told the South London Press: "It's a case of killjoy council. The debate was meant to be about the problem in Camberwell. To broaden it to the whole borough is insane.
"Imagine England fans celebrating World Cup victories. The police can't be expected to run around taking cans off everyone."
The Lib Dems' proposal was defeated by 30 votes to 22 at the Assembly on Wednesday. The executive will now consider the Camberwell ban.