Prime Minister John Key says his visit to Afghanistan last month convinced him to reject Australia's request to take part in a joint Anzac force in Uruzgan province.
If the Government had agreed to the request, New Zealand troops in the province would have been deployed to help train the Afghan army, a more dangerous role than the provincial reconstruction team's work in Bamyan.
Mr Key says the former Australian prime minister, Kevin Rudd, last year asked for up to 50 soldiers to join the Australian contingent in Uruzgan.
The Government considered the request, but Mr Key says after his visit to Afghanistan he turned it down. He says he was not prepared to put New Zealand lives at risk in Uruzgan.
The danger has been underscored by the deaths of five Australian soldiers in Afghanistan in the past month - two of whom were killed by an improvised explosive device in Uruzgan.
Mr Key says Mr Rudd was disappointed but understood the decision.
Govt should reduce NZ role in Afghanistan
Labour leader Phil Goff agrees and says the Government should be looking to reduce New Zealand's role in Afghanistan.
"I don't think we need to be embroiled further in a war which will not be won if the local government there continues to be corrupt and not to win the hearts and minds of its own people," he says.
"Sacrifice is one thing for Kiwis, we accept that, but we need to know that it's in a worthwhile cause and that there is a chance of success at the end of it."
The Government is considering placing support staff in the Australian army's headquarters in Kabul, a move that would involve fewer than 10 staff.