His warning follows a spate of vigilante incidents involving tourist drivers in recent weeks.
The latest saw an incensed Dunedin man snatching the car keys from a tourist who had stopped to take photos on Otago Peninsula, causing eight vehicles to back up on the narrow road.
The police have asked to motorists not to take matters into their own hands.
John Key said today that Kiwi drivers were just as bad as tourist drivers, if not worse, with more crossing over the centre line than tourists.
He said the public should never take the law into their own hands. Instead, they should call 111.
His comments come as a petition to introduce testing for overseas drivers received thousands of extra signatures since 5-year-old Oamaru girl Ruby Jay Marris was killed in a crash on February 21.
A Chinese driver is accused of crossing the centre line on State Highway 1, at Moeraki and crashing into the car she was travelling in.
The petition, launched by Sean, 10, and Cody, 9, Roberts after their father Grant Roberts died in a 2012 crash caused by a Chinese visitor who had only been in New Zealand for one day, now has almost 37,000 signatures. The Roberts brothers have been invited to speak at a parliamentary industrial relations and select committee on March 19.
In the incident in Dunedin, Robert Penman took the the keys off a foreign driver because "I've been in a head-on crash before and I don't want to be in another one".
Today, Mr Penman, a diesel mechanic, said the issue of tourist driving had become so bad in Otago that he would continue to ignore police advice and keep up his vigilante actions in order to try and keep the roads safe.
"It is no different from taking the keys off a drunk driver in a pub car park. It doesn't worry me, as long as it keeps motorists safe," he said.
"I've been in a head-on crash before and I don't want to be in another one. When you see the near misses you see on a daily basis ... well you've just got to do something."
'Waved $50 under my nose'
During the incident two years ago, Mr Penman said he narrowly avoided a head-on collision when a car came around an Anderson's Bay corner on the wrong side of the road.
The driver then did a U-turn in front of traffic and pulled into a side street and stopped in the middle of the road.
Mr Penman says he phoned police, followed them, and reached inside the car and took out their keys.
"He took $50 out of his pocket and waved it under my nose to get his keys back."
Saturday's incident started when Mr Penman saw a rental car parked in the middle of the southbound lane of Highcliff Rd.Eight cars were soon backed up behind the parked vehicle while the occupants took photos of the Otago Peninsula.
Mr Penman said it was not safe to pass and he tried tooting several times. Eventually, the couple went back to their car and drove on at 20km/h.
The rental car later turned into a driveway, with Mr Penman and his son getting out of their vehicle to block their eventual exit.
By that stage, he had rung police.The pair watched as the man and his female passenger changed seats and then she drove towards them with the handbrake on.
The male tourist then got out of the rental car and "started pushing me"."When he started to push me, I went around to the driver's side and grabbed the keys, and I said, 'you are not going anywhere'."
Mr Penman said the tourist then accused him of trying to steal his vehicle, and "I said, 'You have been dangerous driving and I am giving the keys to police"'.
Calm down
Southern District acting road policing manager Senior Sergeant Steve Larking said police spoke to both parties, with the visiting driver given information about where to park safely, while Mr Penman was told to "calm down". No infringement notices were issued.
Mr Penman told the Otago Daily Times he had made frequent complaints to police before about dangerous driving on the road, and "police say they can't get there".
"When nothing proactively is being done about it, I think it is time for change."
He made no apologies about his actions and would do the same again.
In January, a Queenstown man took the rental car keys off a tourist driver on the Lindis Pass after being angered by his dangerous driving.
A visiting Chinese family had to continue their journey by plane last week after Haast woman Sheri Wright confiscated their car keys at Franz Josef because they'd been driving on the wrong side of the road.
A tourist driver of a rented people mover that crashed and killed one person has been charged with careless driving causing death and careless driving causing injury and is due in court this afternoon.
The 39-year-old female Taiwanese visitor was driving with six family members in the car when the crash happened at a stop sign-controlled intersection of Jones Rd and Dawsons Rd in Templeton, south of Christchurch, on February 18.
