Health Minister Andrew Little has shot down calls for a swift overhaul of drug laws, saying any major change would first have to go back to a referendum.
A host of health and social organisations - including the Medical Association, Public Health Association and Mental Health Foundation - have published an open letter, asking for drug use to be treated as a health issue, not a criminal one.
Speaking to RNZ, Little said the signatories had an admirable goal, but should have acted sooner.
"Their gesture today is 12 months too late," he said.
Little said the government was now constrained by last year's public vote on cannabis legalisation, which returned 50.7 percent in opposition.
"I would interpret that as 'no, we're not quite ready for this level of liberalisation just yet'," Little said.
"Doesn't mean to say New Zealand won't be [ready] in the near future, but it would benefit from more public debate and scrutiny."
Little believed, given the referendum's tight margin, the public would expect to have a vote on any further significant drug reform. He encouraged the organisations behind the letter to continue driving a public discussion after which another vote could be held.
"By having a proper well-organised co-ordinated debate about the issue - which we didn't have last year - I think more New Zealanders will be open to looking at alternative ways of regulating potentially harmful drugs."
Little declined to put a time frame on when it might be appropriate to hold another vote, but noted that it was not his top priority.
"The more we can have a discussion about it... then the sooner judgments can be made about when to go back to the public for a decision."
Green Party MP Chlöe Swarbrick, who has been trying build cross-party consensus on decriminalisation, said she was baffled by Little's refusal to move on drug reform.
She said both the mental health inquiry and the Safe and Effective Justice review recommended an overhaul of the Misuse of Drugs Act.
"It seems like an absolute abdication of political responsibility," she said.
"What on earth is the point of being elected to Parliament and having such an overwhelming mandate, if not to undertake the things that you believe in?"
The government must not "throw out the baby with the bathwater" simply because of the referendum result, she said.
"There was a very narrow, very specific law that was shot down by a narrow margin. Of course that means that law can't progress, but it doesn't mean we stop talking about the issue."
JustSpeak, an advocacy group for criminal justice reform, helped organise the letter and director Tania Sawicki-Mead said she was frustrated by the minister's response.
"It's fundamentally disappointing and really out of step with the so-called compassion that this government has said it wants to lead with."
Mead said it looked like Labour had deemed the subject too politically risky and did not want to lose some the voters it won over from National at last year's election.
"I do think there is a misread of the mood here. The fact that this open letter has been signed by people who were very vocal opponents of the cannabis referendum ought to be a signal to this government that there is a far greater consensus on the need for a health-based approach than they perhaps realise."
She pointed to a recent UMR poll, commissioned by the Helen Clark Foundation, which found 69 percent of voters either supported cannabis legalisation or would support decriminalisation.
Little told RNZ he took that poll with "a grain of salt".
Prime Minister Jacinda Ardern, speaking to media after the weekly Cabinet meeting, said she acknowledged the point raised by the organisations.
She said police were now obliged to take a health-based approach unless it was not in the public interest.
Since that change was adopted, the number of cases going to court declined, she said about 40 percent for certain drugs, 20 percent for cannabis.
"What I'd like to do now is to dig into that into more detail," she said.
"Is it achieving the goal we set, which was a health-based approach, or are we seeing a bit more of a subjective approach being taken?"
She said it would be helpful if Parliament took a bipartisan approach to this issue.
"I really would challenge, for instance, the National Party to consider their position on this issue because they criticised us when we did that.
"I would like to see whether or not Parliament can reach some consensus."