Te Mata Park Trust chairman Bruno Chambers said there was a blanket ban on fireworks in the park.
"It is a real disappointment but it is kind of what happens at Guy Fawkes, I'm afraid," he said.
"This is the time of year we do have problems. The month after Guy Fawkes it is usually a lot drier this time of year so it is unusual for a fire to take hold with this moisture around - while it is still so green.
"The problem is going to be a lot worse in the coming summer because grass will be a lot longer, ranker and more of a fire risk.
"If anyone at all sees somebody with fireworks they should call the police straight away, to help nip it in the bud.
Fireworks were not his only concern.
Anything could be a problem - any cigarettes or people being careless with flames will be a real issue.
Mr Mitchell said a camera-mounted drone used to assess the fire, being trialled in the region this week, was "a very helpful tool".