Nazir Afzal, whose nephew was stabbed to death in the street earlier this year, said: "Children and young people don't know how to talk to anybody anymore.
"They speak to people online.
"When they face people in the street in the real world, they don't know how to de-escalate a situation."
Speaking at a conference in London discussing knife crime, so-called county lines drug gangs and child sexual exploitation, he said the typical response online is to retaliate and escalate if someone is confronted and the "isolation of young people" was a real concern.
He told the audience at the event organised by Resolve, which works to tackle anti-social behaviour: "They are not talking to each other. They are not meeting up and learning certain skills.
"The Government is not interested in that side of it because it's difficult.
"We need more police officers, youth services and children's services."
He said the prevalence of organised crime and social media were also factors in the problem.
Preventing crimes from a young ages
The number of first-time knife crime offenders has risen by 25% in the last five years, with more than 14,000 caught in the year to June, official figures released last month showed.
The proportion of repeat offenders sentenced who had previous convictions for similar crimes has also jumped to nearly 30% (5,774), its highest level on record, according to Ministry of Justice (MoJ) data.
Anthony Peltier, Assistant Chief Officer at the Metropolitan Police who won an award for helping to save the life of a stabbing victim, said carrying a knife had become "an accessory" like having the latest mobile phone.
Mr Peltier, also a former head teacher who told the audience one of his sons was once arrested for carrying a knife he had bought to put on display at home, said he had heard of children as young as eight taking a weapon to school.
He added: "The problem has not gone away, if anything it is rising.
"There's no intention to go out and hurt somebody.
"They (young people) think that it's what they should be doing."
The member of the Violent Crime Prevention Board and volunteer with the Passion Project, which looks to support young people, said: "We can't keep talking about money and programmes that are funded by the Government and funded by the police, because they are not sustainable.
"When the budget changes, the initiatives fall away. We need to have a different approach."
He wants to see violent crime prevention boards set up across the UK which are made up of volunteers.
Baroness Helen Newlove, the former victims' commissioner until earlier this year, said: "We need to turn the tide.
"The level of violence that is now accepted is surely unbelievable and should not be tolerated.
"We don't have police officers on our streets, we don't see our councillors."
Baroness Newlove, whose husband Garry was killed outside his home after confronting vandals in 2007, claimed incidents such as cars being set on fire and bricks being thrown through windows were commonplace and not being tackled, and there was "too much bureaucracy" which could hinder change.
She added: "Communities are threadbare and kids have nothing to do.
"We shouldn't put up with it anymore."
She vowed to carry on challenging the government - whoever may be in power - joking that at present politics seemed a bit like a "mad tea party", adding: "I've said to Government I'm prepared to roll my sleeves up and help communities again.
"Too many lives are still being lost and too many communities are not being heard by agencies that are meant to protect them."