Nutter said on Monday he would outline elements of a broad plan - which he called a "more holistic approach" - to crack down on flash mobs and address the needs of young people and families.
"Some will be positive," Nutter told the congregation. "Some of them you won't like."
Before his roughly 30-minute speech, Nutter warned church members that he would say things that they occasionally may think, but not say. He took the time to note that there were good hard-working people in the city and many upstanding young people.
But, in a fiery and firm speech that elicited applause, praise and chuckles, he condemned young people involved in flash mobs, saying they will be punished. He scolded neglectful parents, particularly some African-American fathers, challenging them to be more involved.
"Parents, get your act together," he said to applause from members in the wooden, red-cushion pews.
He continued: "You need to get hold of your kids before we have to."
He said neglectful parents would face criminal charges.
Nutter, a father of two, including a teenage daughter, said men need to participate in their children's lives, mentor, discipline and teach them - not just be a "human ATM" or a "sperm donor." "That's not good enough. You can do better than that."
"A particular problem in the black community is we have too many men making too many babies that they don't want to take care of," he preached to applause. "We end up dealing with your children."
He continued: "The immaculate conception of our Lord Jesus Christ took place a long time ago, and it didn't happen here in Philadelphia. So everyone of these kids has two parents who were around and participating at the time. You need to be around now.