Prime Minister Bill English says he backs the defence services 100 percent, amid allegations about the military's involvement in civilian deaths in Afghanistan.
In their new book Hit and Run, investigative journalists Nicky Hager and Jon Stephenson said six civilians died and 15 were wounded in raids led by SAS soldiers in 2010.
They said there needs to be an inquiry - something three New Zealand human rights lawyers, acting for the Afghan villages involved - agree with.
Labour, Green, New Zealand First and Māori parties have also called for an inquiry, and United Future leader Peter Dunne said that one was inevitable.
Mr English said there was no evidence the SAS soldiers were anything but professional.
"Clearly in these circumstance there is some disagreement over what happened.
"But we haven't seen anything that indicates that they have acted outside their rules, or any indication they haven't acted with complete professionalism."
He said he could not say how long it would take to make a decision about whether to initiate an inquiry.
Mr English is to meet with the Minister of Defence Gerry Brownlee and the chief of defence Tim Keating tomorrow.