Prime Minister John Key says the Government will decide in November whether it will join Australia in a legal challenge against Japan's whaling in the Southern Ocean.
Australian Prime Minister Kevin Rudd has given Japan until November to stop its whaling programme, or face legal action in the International Court of Justice.
Mr Key says the Government has made it quite clear that New Zealand is opposed to whaling in the Southern Ocean.
He says it would prefer a diplomatic solution to the situation, but if that fails, then the Government will consider the legal challenge.
Mr Key says a court case takes a long time and if saving whales is really the aim, then a diplomatic solution will be quicker.
Earlier, Foreign Affairs Minister Murray McCully hit back at claims New Zealand is taking a softer stance against Japanese whaling for fear of harming trade relations.
Anti-whaling group Sea Shepherd has criticised New Zealand for not following Australia's lead in giving Japan an ultimatum to stop whaling.
The protest group says the New Zealand Government is putting trade interests ahead of its duty to uphold international law.
However, Mr McCully dismisses that as a ridiculous assertion. He says the Government is concentrating on diplomatic efforts, but has not ruled out future legal action.
The Labour Party says New Zealand should join forces with Australia and take legal action as diplomacy has already failed.
But the minister says a legal challenge would not be an open and shut case in favour of the New Zealand and Australian position. "If it was, then probably we'd have pursued it more quickly," he said.
Mr McCully says it should be apparent in a matter of weeks whether diplomatic efforts have been successful.