He was going to report it to Auckland Mayor Len Brown today.
"It brought this simple pleasure to the waterfront, just sitting and listening to that piano being played. I really am saddened."
Mr Harvey said there was 24-hour security at the waterfront but no CCTV cameras in Silo Park to capture the attack.
"I guess it's just called life in a big city"
He vowed to put a new piano on the waterfront by Christmas.
"We're not going to be daunted by this. I promise we'll get music back on the waterfront."
The piano was a family heirloom and was gifted to Auckland Council for public use.
It is estimated to be at least 100 years old.
Waterfront Auckland spokesman Luke Henshall said the damage seemed to have been inflicted in a random act of vandalism.
Piano repair specialists had been called in to find out whether it could be fixed.
"We are obviously gutted that someone has chosen to vandalise what is a treasured icon of Wynyard Quarter. The public piano has been hugely popular since it was introduced with the opening of Wynyard Quarter in August last year, with a number of regular daily users.
"The initiative was carried out on a platform of trust and we're disappointed someone's chosen to push that trust too far."
Mr Henshall said it was hoped the piano could be returned to its place on the waterfront if its damage was repairable.
Commenters on the Waterfront Auckland Facebook page also expressed dismay at the attack.
Lisa Struneski said: "What is wrong with some people.. disgraceful!"
Tim Gummer said the piano should be replaced:
"I loved that the piano was just out there... We shouldn't give into anti social wreckers."