The police minister says it is important he gets officers back to their core crime fighting role.
The police will begin to reduce their response to mental health callouts from November, and are already testing a change to how they prioritise lesser-risk 111 callouts.
A briefing from July shows police saying they would "refuse 'inappropriate' requests for help from hospitals".
Mark Mitchell was asked what the threshold was that would make a request "inappropriate".
"That's operational and that'll be worked out between police and health," he said on Thursday.
"But our expectations are there is a seamless transition, and a well-planned transition, but that work is happening."
Officers could not be spending hours in ED, he said. He provided an example from a nightshift he went on, where two officers spent the whole shift in hospital with a young woman who was thinking of self-harm.
"As police minister, it's really important that I get those police officers back on their core role."
Health NZ did not begin planning how to manage the extra demands from November on their staff, until after police told the agency about the police timeline for reducing services, which they made public only at the end of August.
The Health Ministry said in July it was about ensuring "that everyone stays safe as the changes bed in".
Mitchell and Mental Health Minister Matt Doocey have to take more details about the transition plan - the entire thing runs over five years - to Cabinet in November.
"Health is definitely going to have to build capability, there's no doubt about that - but there's a commitment," Mitchell said.