A statement from Waitemata police district commander Superintendent William Searle said police considered the image to be staged.
"The images record a police officer's participation in a charity fundraising event, but are not appropriate.
"Until such time as the full circumstances are established we are not in a position to comment any further."
On the internet forum where the picture was published, users speculated on whether the picture was of a real officer or a hoax.
Several message writers said they thought it was unwise and others called for it to be removed.
The person who posted the picture seemed to have a change of heart after the comments and removed the image.