"Last year, thousands of New Zealanders wrote letters and signed petitions calling for an inquiry into mental health and addiction. This was resisted by the then National government," he said.
Doocey, who is a member of the heath select committee, also wrote to Clark on September 11, requesting a briefing on the inquiry when it was available.
Clark said he was happy to provide Doocey, and the health select committee, a briefing on the inquiry's findings "at the earliest opportunity".
Green Party mental health spokeswoman Chloe Swarbrick also declined to consider any further cross-party collaboration on mental health until after the inquiry had reported back.
In a letter to Doocey following a discussion last week, Swarbrick said she had been working for six months to create a cross-party group on drug harm reduction. That group had now met four times, discussing issues that included the link between mental health and substance abuse.
"While I was disappointed that National did not want to be officially involved in the group, I've been pleased to have had members from every political party in Parliament join the group's meetings," she said.
Swarbrick told Doocey it was now best to wait until after the inquiry to meet to discuss building on the work of the inquiry and her own cross-party group.
Clark told the Herald the Government's focus was the inquiry, which was set up during the coalition Government's first 100 days in office.
Dealing with mental health and addiction issues are in both of Labour's agreements with coalition partner New Zealand First and confidence and supply partner the Green Party.
"In the wake of the report there will be a real opportunity for parties across Parliament to show their support for the findings and to talk about how they should be addressed. But it doesn't seem like the time right now to seek another vehicle for conversations. The public won't be particularly interested in an internal talkfest among politicians. What they'll want to see is real action," Clark said.
He said the inquiry would inform his bid for funding in next year's "wellbeing Budget", and Finance Minister Grant Robertson was aware of the public's expectations around mental health and the review.
"Partly the timing of the report back is time so it can feed into the Budget process," he said.
