He has characterised the deal reached at the United Nations conference as "short of the aspirations and expectations" that people held, while Green Party co-leader Jeanette Fitzsimons has labelled it a "tragedy for humanity".
Labour Party climate change spokesman Charles Chauvel, who also attended the conference, said the deal could be built on.
The UN talks ended with a bare-minimum agreement that fell well short of their original goals after prolonged negotiations failed to paper over differences between rich nations and the developing world.
Critics have complained the explicit deal struck to limit global warming to 2 degC provided no details of how this goal would be reached, and that the emission cuts that were promised would be insufficient to get there.
However, Mr Key said New Zealand individually had made good progress in some areas.
"We want to have the rules altered to allow us to harvest forests that are pre-1990 and re-plant them in other parts of the country. We also want to have the position where we can lock up emissions where wood is harvested but used in the production of furniture and the like (rather than have it count as being consumed and its emissions released on felling)," Mr Key told Radio New Zealand.
"In the course of negotiations over the last week significant progress was made on nations accepting those rule changes but like everything here at the moment that isn't something that has been ratified by all the countries.
"From New Zealand's point of view we can come away and say it's been a victory, in so much that we have made progress in the changes to the rules, subject to them being ratified."
New Zealand's initiative to get global cooperation on research to reduce emissions from agriculture had also gone down well.
In New Zealand, Deputy Prime Minister Bill English said leaders made the best of the situation they found themselves in.
"From New Zealand's point of view we've still got our national interest to negotiate for and we haven't given anything away in this round." Mr Chauvel thought considerable progress had been made around verification of different countries' reductions and on help for developing countries to adapt.
"The momentum of this progress needs to be built on. At the same time, much more work is needed to set out binding and appropriate targets for both developed and developing countries."
New Zealand needed to do its part and set a more ambitious target, Mr Chauvel said.
New Zealand's conditional target for reducing climate harming emissions is to reach 10-20 percent below 1990 levels by 2020, and Mr Key says a stronger target would hurt the country's economy.
Ms Fitzsimons saw the deal as a failure "papered over with some fine-sounding words by (President Barack) Obama".
The purpose of the meeting was to agree on a second commitment period for the Kyoto protocol but that had not been achieved, she said.
"We came here wanting an ambitious, fair and binding agreement. The talks have failed on all three counts.
"There are no country targets, only an appendix where countries offer non-binding reductions which collectively will not stop warming of 2 degrees. As it is not ambitious or binding, it cannot be fair to the developing countries that are already suffering from climate change."
