"Stop waiting for Jesus to come," Cosby said from the steps of Bible Way Baptist Church, telling the crowd of about 300 to be better guides for their children.
His remarks ended an 11-block march against violence Monday sponsored by Men United for a Better Philadelphia, the Philadelphia Inquirer reported Tuesday.
The Philadelphia native led the march with West Philadelphia community leaders and Democratic mayoral candidate Michael Nutter, who pressed marchers to "put the guns down."
Philadelphia, with at lest 169 homicides reported through Monday, is on pace to exceed last year's 406 murders, the most since 1997, the newspaper reported. Handguns were involved in most of the killings.
During an evening rally, Cosby placed much of the blame for urban gun violence at the feet of parents and adults who do not provide structure and guidance to children.
Cosby, who has a doctorate in childhood development, urged parents to monitor their children's activities and embrace non-violence, adding, "We're tired of funerals."