Leif Larsen, 61, was "one of our best and most experienced diplomats" who was "very respected by his colleagues," Foreign Minister Børge Brende told reporters, adding that his Pakistani counterpart had told him the causes of the crash "could not be fully explained yet."
"This will be investigated," and the Pakistani authorities have already "established an investigation committee," Brende said.
Larsen, married and the father of one, had been stationed in Islamabad since 2014.
The ambassador was killed, along with the Philippines envoy and at least five others, when the military helicopter they were travelling in crashed on a school in a remote area of the Himalayas.
The Taliban in Pakistan have claimed responsibility for the crash, claiming they downed the helicopter as part of a plot to kill Prime Minister Nawaz Sharif, who had been travelling to the same region in a plane.
It was not immediately possible to verify the Taliban claim and the northern region where the chopper came down, Gilgit-Baltistan, is not known as a stronghold of the militant organisation.
Larsen was at the Hotel Serena in Kabul, when it was attacked by the Taliban 2008, seriously injuring one of his colleagues from the foreign ministry and killing Carsten Thomassen, a journalist with Dagbladet.
"It could just as easily have been me. It was pure coincidence that I was down in the basement," Larsen told the Moss Avis newspaper at the time.
He went on to become Norway's special envoy to Pakistan and Afghanistan, starting as ambassador to Pakistan in September.
"We'll show the Taliban that we are serious. We will not be intimidated out of Afghanistan, but on the contrary, continue our efforts to help Afghans lead a normal life," he said.
Prior to his involvement in Pakistan and Afghanistan, Larsen held positions in Saudi Arabia, Iceland and Norway's delegation to Nato over a 29-year career in the foreign ministry.