Under the plans announced on Tuesday, police can search people without reasonable suspicion.
But London Assembly Green Party member Jenny Jones said the stop and search powers may alienate young people.
Lambeth Green Party Crime Spokesman Shane Collins said:
"We welcome any move that will reduce the scourge of knife crime. But people in this Borough remember what happened in the 1980s when police were encouraged to use stop and search powers indiscriminately. Police bullying of poor teenagers from ethnic minorities will do nothing to help reduce the social exclusion that is the real cause of youth violence.