Harper's comments came Friday in Vancouver in response to a question at a brief news conference following an event at a downtown science centre.
"No, it will not happen under our government," Harper said. "We're very concerned about the spread of drugs in the country and the damage it's doing and as you know we have legislation before the House [of Commons] to crack down."
This week, four former Vancouver mayors endorsed the Stop the Violence Coalition, which is comprised of former police officers, a judge, medical leaders and B.C.'s former chief coroner.
The coalition's founding principle is that regulation and taxation of marijuana would stop most of the violence associated with the drug trade and make pot less accessible to children.
Current Vancouver Mayor Gregor Robertson has said he agrees with the coalition's goals.
"We see the impact on the streets. We see the gang activity that's largely funded by the marijuana trade, a huge industry here in B.C.," Robertson said. "There's no tax revenue flowing from [it]
, so I think it's time for reform."
Protester's bike damaged
About 60 protesters gathered outside the science centre during the prime minister's visit, but tight security kept them at bay.
There were no injuries or arrests, but one protester's bicycle was damaged as the van carrying Harper was being driven away from the morning venue.
"My wheel has been taco-ed," said Holly Hendrigan.
Another protester, Mathew Cagis, said he saw what happened.
"As soon as the van went by, I heard the crunch and grind," Cagis said.
A man in street clothes, who identified himself as an RCMP officer, stepped forward and said the bike would be repaired.
"We will take care of it. I just need your name and phone number, ma'am. I apologize for that," the officer said.
Hendrigan asked if the prime minister had a bike repair person in his entourage.
"We will do what needs to be done to make it right," the officer said.
Earlier, Harper and B.C. Premier Christy Clark announced the federal and provincial governments are each contributing $10.5 million to the $35-million renovation and expansion of the science centre, now called the Telus World of Science.
The prime minister's visit to Vancouver continues through Sunday, when he will attend the Grey Cup game at BC Place Stadium.