Imam Ammaar Domun, of UKIM Masjid Ibrahim and Islamic Centre, said youngsters felt like they are being held hostage by certain people.
"What is being done to disrupt the work of these individuals? We know where these gang members are," he added.
The meeting heard the Met is conducting covert operations against gangs, but it could take weeks or months for results.
Supt Waheed Khan admitted there are things the Met can do to improve, adding it was important the police, council, schools and community all play their part.
"Where there are shortfalls, [the Met] will seek to address them," he added.