Sky Television has been fined $4000 for showing extensive footage of the 15 March terrorist attacks taken from the alleged gunman's livestream.
The Broadcasting Standards Authority concluded that the clips were highly disturbing and should not have been aired.
The authority found that the footage, which aired on Sky News New Zealand, had the potential to cause significant distress, particularly to the family and friends of the victims, and the wider Muslim community.
Authority chairperson Judge Bill Hastings said the level of public interest in detailed depictions of violence shown was not proportionate to the high level of harm that could be caused to viewers.
"There was high value and public interest in keeping the public informed about these events as they unfolded," he said.
"Following the attacks, broadcasters needed to balance their duty to provide sufficient information and detail to the public, while also avoiding harm to viewers. This weighing exercise took place during unprecedented and challenging circumstances, as events unfolded and as new information came to hand."
The authority found that the level of public interest in the detailed depictions of violence shown in the clips from the livestream video was not proportionate to the high level of harm that could be caused to viewers.
Authority chief executive Belinda Moffat hoped the decision would provide guidance to broadcasters on how broadcasting standards apply when reporting on crisis and terrorist events.
"We hope that these decisions will prompt discussion with broadcasters about whether any changes to the codes are required to provide additional guidance," she said.
"We will seek broadcasters' views on whether further guidelines are required for foreign pass-through channels, particularly around the action expected from local broadcasters during extreme circumstances.
"We are also assessing whether the codes should include principles for reporting on terrorist activity."
The authority did not uphold three other complaints against TVNZ, for naming the alleged attacker, showing a brief excerpt from the livestream video, and showing footage of identifiable victims being taken to hospital.
This story originally appeared on Radio New Zealand.