A 47-year-old man has been arrested over an attack on Green Party-co-leader James Shaw.

Shaw, 45, was attacked in Wellington on his way to Parliament on Thursday. A spokesperson said he was grabbed and hit in the face by one person.

Two members of the public helped him, and the spokesperson said Shaw is "very thankful for their assistance".

Newshub understands Shaw has bruising around his eye from the incident.

Wellington police Snr Sgt Matthew Morris said on Thursday the assault took place at around 7:50am outside the entrance to the Botanical Gardens in Wellington.

"We understand members of the public have assisted the victim and we believe there may also be other witnesses to the incident," he said.

The Climate Change Minister went to hospital for a precautionary check-up, despite turning up to work "chipper", his spokesperson told Newshub.

Shaw has received messages of support from politicians on both sides of the spectrum, with National leader Simon Bridges saying on Twitter: "Violence is never ok. From myself and the National Party we wish James Shaw a fast recovery."