Prime Minister John Key said it would been better if Green MP Marama Davidson had not taken part in a Gaza flotilla, saying it was a "less than perfect look."
Davidson is among a group of women detained by Israeli authorities overnight on a protest ship trying to breach Israel's blockade of Gaza.
Key said he was not surprised by the development given it had happened to previous protest flotillas and the Ministry of Foreign Affairs had advised people not to go.
Asked if it was appropriate for an MP to take part in such a protest, he said: "It probably, to be frank, would be better if they didn't. But I think that's going to fall on fairly deaf ears when it comes to those sort of protests from the Greens."
"It's less than a perfect look, but she would have been well and truly aware of that. This isn't the first flotilla that's gone into the Gaza and they've all ended pretty much the same way."
He said New Zealand's foreign affairs officials would provide whatever support was needed but it was likely Israel would deport Davidson.
Green Party co-leader Metiria Turei said Davidson knew it was likely she would be detained by Israel for taking part in a Gaza protest flotilla but believed the risk was necessary.
"It has happened before and the point of the flotilla is to highlight the blockade, that's why Marama went. That's why she put her body on the line was to highlight the humanitarian crisis in Gaza that is caused by the illegal blockade."
A spokesman for the Ministry of Foreign Affairs said its Embassy in Ankara would provide assistance should Davidson require it.
"The Ministry's travel advice explicitly advises New Zealanders against any attempt to enter Gaza by sea in breach of Israeli navy restrictions, or participating in any attempt to break the naval blockade, including participation in flotillas to deliver aid, due to the risks involved."
The Zaytouna-Olivia ship carrying the 13 women was intercepted by the Israeli Navy about 35 miles off the coast of Gaza.
It is now being taken to the Israeli port of Ashdod where the women were expected to be deported.
In a statement, the Israeli military said the takeover was without incident.
It had tried to stop the boat through diplomatic channels before intercepting it. It said the blockade was lawful and this was an intentional attempt to breach that blockade.
"In accordance with international law, the Israeli navy advised the vessel numerous times to change course prior to the action.
Following their refusal, the navy visited and searched the vessel in international waters in order to prevent their intended breach of the lawful maritime blockade of the Gaza Strip," the statement said.
In a video on the Kia Ora Gaza website which was pre-recorded in case the flotilla was detained, Davidson said there was no reason to detain the women.
"We are peaceful women who started by principles of peace. The Israeli oppression forces had no reason to kidnap us, to take us hostage. They could have just let us through to Gaza.
We need the world to pressure the Israeli Government for our immediate and safe release."
Davidson set off in September to join the Womens' Boat to Gaza which was sponsored by the Freedom Flotilla Coalition, pro- Palestinian groups mainly in Europe.
Others on board include Norther Ireland's Mairead Maguire, the 1976 Nobel Peace laureate, retired US Army Colonel Ann Wright and Fauziah Hasan, a Malaysian doctor.
It was captained by Australia's Madeline Habib.
In 2010, an attempt to breach the blockade by a Turkish flotilla ended in the deaths of 10 activists and wounding of two Israeli soldiers after a fight when the soldiers boarded the ship.
Israel claims the blockade is necessary to prevent Hamas from obtaining arms and supplies to use to attack Israel.