Andrew Little has taken a hard stance against people throwing objects at politicians, following a sex toy being hurled at senior minister Steven Joyce last week.
The video of the incident made global headlines, though the Prime Minister believes the stunt's anti-TPP message would have been lost because of it.
After the incident, Mr Joyce later tweeted saying someone should send US comedy show host John Oliver the footage of the incident "so we can get it over with".
In the past, Oliver has taken a liking to New Zealand current events, featuring on his Last Week Tonight show including the submission for an alternative flag design and John Key's ponytail-pulling antics.
Mr Little said encouraging others around the world to show the footage could turn New Zealand into a laughing stock.
"Yeah, we should have a laugh around here perhaps, but sending it around the world so the rest of the world continues to laugh at us? We have become a laughing stock under John Key's government.
"It's not good when our senior Government politicians seem to think it is ok for the rest of the world to laugh at us. The rest of us might have laughed about what happened to Steven Joyce, but the reality is throwing things at politicians? What if it wasn't what it was? What if it was something much harder? It wouldn't have been a good thing," he says.
He believes throwing things at politicians shouldn't be egged on, regardless of how funny it might be afterward.
"It shouldn't be encouraged throwing things at politicians no matter how angry you are at the policies. There is a right way to protest, and people should protest and take their issues up, but I don't think this was the best way to do it."
Protester Josie Butler, who threw the object, said her actions were to "gain awareness about the atrocity that is the TPP".
At the time, she yelled: "That's for raping our sovereignty".
John Key wasn't impressed by the stunt, saying the Government would be happy to discuss the TPP with those opposed to it.
"What she did actually is she created an image that went everywhere, went totally global.
"No one internationally is going to look at that and say `it's TPP', they're going to say it's some woman throwing a dildo at a minister," he said on the Paul Henry programme this morning.