The Prime Minister isn't surprised Green Party MP Marama Davidson was detained while on a peace flotilla Gaza, but she'll get consular help if she needs it.
Ms Davidson is among a number of others on the Women's Peace Flotilla which left for Gaza on September 21 to protest Israel's decade-long blockade.
She was one of 13 women aboard the Zaytouna-Olivia which was intercepted in international water and towed to Ashod by the Israeli navy.
Her party is calling on the country to let the group go.
"We are calling on Israel to swiftly release Ms Davidson and the rest of the crew of the Zaytouna-Olivia, and to end the illegal blockade of Gaza," said Green Party Co-leader Metiria Turei.
"This inhumane blockade has been in place for a decade, resulting in plummeting living standards and health services, high unemployment, and severe food insecurity for the people of Gaza."
John Key says the outcome was predictable, given all other flotillas trying to get to Gaza ended the same way.
He says advice from the Ministry of Foreign Affairs and Trade would be not to go on the trip.
"Probably to be frank, it'd be better if they didn't, but I think that's going to fall on deaf ears when it comes to that kind of protests from the Greens.
"It's a less than perfect look [for New Zealand], but she would have been well and truly aware of that," he says.
Mr Key says there'll be a process for her and the others to go through, with deportation the likely outcome which would probably be paid for by Israel.
"We'll make sure she's, as best we can, appropriately looked after and giving her the support she needs."