Among those targeted was a four-year-old child and a dozen people on a family outing.
The incident happended in October when a Polynesian family attended the game in Roosevelt, Utah, to watch a relative play his final game for Union High School. His team lost, to finish the season without a win. To cheer up the squad, the men and boys of the family performed a haka.
Officer Luke Stradinger, who ordered the use of pepper spray, apologised in a report for causing “discomfort” to innocent bystanders, but said he wasn’t familiar with the haka and only acted because the group was blocking the only exit.
“I have never seen such an event, or even heard of such a thing,” Mr Stradinger said.
The American Civil Liberties Union said the incident amounted to a breach of the right to free cultural expression.