Mr Sabin said there was not too much damage but repairs would have to be carried out.
"Someone's gone to weeks and weeks of effort to do that, and someone's come and set fire to them."
Tauranga Mayor Stuart Crosby said it was sad to hear of the damage to the new instalments.
"It's a desecration of a site that's very historic to Tauranga, both from a Maori perspective and a European perspective.
"It's just a silly event and should not have happened, and it does not reflect Tauranga at all.
"It's very rare. Down on The Strand there are carvings and on the new Harbour Link [which are undamaged]. Regrettably, it does happen from time to time."