People associated with the protest at Parliament were seen licking their hands before pressing the button at a pedestrian crossing in central Wellington.
Authorities are calling for members of the public to report these types of incidents so they can review CCTV footage and find those involved.
A Wellington resident said he first saw it happen at the corner of Waterloo Quay and Bunny St - less than 500 metres away from Parliament - on Monday morning.
"I wasn't sure if that's what I saw. It wasn't until I was standing next to one of them and he pretty blatantly did it," he told the Herald.
The second time he saw the same thing happen, later that day, he said he immediately realised what protesters were doing.