Police would continue to maintain vigilance on the roads, he said.
Initial indications showed that alcohol and speed had been factors in at least eight of the deaths, he said.
This holiday period toll was "tragic", but not a long-term trend.
He answered criticism that the police's focus on speed was not working by saying they based their road policing policy on proven scientific evidence and not individuals' opinions.
The official holiday road toll started at 4pm on Christmas Eve and finished today at 6am.
The latest reported death happened about 1.50am today, when a man's vehicle crashed into a lamp-post in Christchurch.
It followed the death of a man who had been thrown from the back of a ute on Boxing Day who died yesterday from his injuries in hospital.
That death occurred just hours after a motorcyclist was killed on a South Island mountain pass.
Last year, when the official holiday period was three days shorter than this year, there were seven road deaths. Over the period before that, there were six deaths - a dramatic drop from the 19 deaths over the 2011-12 period.
The highest holiday road toll was in 1972-73, when 37 people died.
Mr Cliff said it was devastating that so many people had lost their lives these holidays and it was due to the same common factors.
"It is a bad decision to drive after drinking. It's that simple."
Mr Cliff said police and emergency services around the country had attended numerous crashes this holiday period and unless driving behaviour changed, they would be attending hundreds more this year.
He said police would continue to focus their efforts on reducing the death and trauma from crashes.
"But we all have a role to play, so to all New Zealanders, all family members, all friends, please slow down on our roads."
Associate Transport Minister Craig Foss said any death or serious injury on the roads was one too many.
"Provisional data suggests alcohol, speed or both contributed to 12 of the holiday period fatalities. So many of these accidents, and the pain and suffering they cause, are avoidable. Give yourself the best chance of survival by driving to the conditions, wearing a seatbelt and avoiding alcohol before getting behind the wheel," he said.
Toll
Jan 5: A driver was killed when his vehicle hit a lamp post in Christchurch at 1.50am.
Jan 4: A passenger who was thrown from the back of a utility vehicle onto rocks in Raglan on Boxing Day died in hospital.
Jan 3: Anthony Clifford Sparrow, 50, of Ashburton, died when his motorbike left the road on SH73.
Jan 2: Garry Andrew Wendt, 68, from Ngaruawahia, died in Hamilton after three vehicles crashed.
Jan 2: Martin Cadden, 22, died after he lost control of his car and hit a tree in Canterbury.
Jan 1: Paul Ruben Kasper Kapica, 24, from Kerikeri, died after the vehicle he was driving rolled on Papamoa Beach, Bay of Plenty.
Jan 1: Lavi Taimani, 22, was a passenger in a car that crashed into a pole on Auckland's Southern Motorway. She died at the scene.
Dec 31: A 50-year-old man died after crashing his motorbike in sand dunes at Port Waikato.
Dec 30: Chilyoung Kim and Young-Mo Sang, both 59, from Seoul, South Korea, died after their car crashed off a single-lane bridge in Westland.
Dec 29: A 61-year-old woman was killed when a car and a truck collided on SH1 at Greta Valley in Canterbury.
Dec 28: Two people died after a collision between a car and milk tanker in the Bay of Plenty.
Dec 28: A 56-year-old motorcyclist died after a crash near Hurunui.
Dec 27: Jamie Shane Webb, 25, was electrocuted after a car crashed into a power pole on a rural road in Glentui, Canterbury.
Dec 26: Kevin Keane of Timaru died after the rental car he was driving collided with another car in the Bay of Plenty.
Dec 26: Pengxiao Tao, 22, known as Jessica, died after a campervan and car collided on the Athol Five Rivers Highway in Southland.
