Mr Mackay had told the Times-Age there were about half a dozen trees pupils climbed and he refused to paint height limits, though taller trees were always out of bounds.
"Risk is part of learning and yes, we have had some children fall out of the trees. But nobody has been seriously injured and none has ever fallen out of a tree twice. They learn," he earlier said.
Reportage of the ban had prompted comment across the country, Mr Mackay said, from parents and pundits to the head of Worksafe New Zealand Gordon MacDonald and the Workplace Relations and Safety Minister Michael Woodhouse.
Mr Woodhouse yesterday told media host Paul Henry the impending laws would not stop children playing in playgrounds and "anyone who says that has been very badly misinformed".
"Any school that has good sensible policies right now should have nothing to fear about Monday," the minister said.
Mr Woodhouse also blamed some safety and health consultants for "peddling fear to try and drum up business".
Mr Macdonald said schools were not expected to "stop kids being kids and taking low-level risks" and the new law "was not about banning everything and removing all risk at any cost".
"What might be reasonable is to expect the school to make sure that they take down any trees or branches that are dead and rotting". Or that they prevent kids from climbing trees with limbs that extend out over a public road," he said.
"If you believe some of the stuff written about the Health and Safety at Work Act you might think it will ban just about everything. Kids will have to stop climbing trees, fun runs won't be run, and even coat hooks will fall foul of the law.
"Guess what? It's not true," he said.
"Kids have always climbed trees, and some of them have fallen and hurt themselves. I doubt that will change any time soon," Mr Macdonald said. "The law has long since required schools to manage risks but we've not prosecuted just because a child fell out of a tree. And I don't expect that to change either under the new law."
Mr Mackay said a television news crew had been at the school filming for most of the morning yesterday and he was aware of the comments from Mr Woodhouse and Mr Macdonald.
"There's been comment from all directions to be honest from, you know, the 'principal needs more balls' to totally supportive," Mr Mackay said.
"You can't predict everything but as a school we still believe that exposing children to risk that is suitably managed is important. We definitely want to be in a position where we want our kids to climb trees and to continue to be kids," he said.
Mr Mackay had earlier canvassed the Ministry of Education and said some wording in the act was too vague and open to interpretation.
"The main term that has us concerned, that we needed to clarify before we do anything else, is that we must do all things 'reasonably practical'.
"Nobody has been able to define that for us. What does that mean to a parent whose child has been hurt, what does it mean to Worksafe? Is breaking an arm in a fall reasonable? What about a neck?" he said.
