A video posted on YouTube showed coach Martin Tremblay, who was wearing shoes, trip a 13 year-old player on the opposing team by pushing his skates out from under him following a game at Vancouver's Thunderbird Arena in June.
The boy, who injured his wrist, fell into another player, also knocking him off his feet. The second player was not hurt.
Tremblay could be seen shouting something at the first player he tripped after he fell.
The video has since been removed from YouTube.
Tremblay, who was charged in September, did not appear in Richmond court Tuesday but entered a guilty plea through his lawyer, Bob Bellows.
Bellows said Tremblay has also written a letter of apology and asked the young victims' forgiveness. The lawyer said Tremblay was under a lot of personal pressure just before he committed the offence.
"It's fair to say he had a significant number of stressors to deal with at the time and he simply didn't have the energy to deal with it properly and he came up short," said Bellows.
Tremblay is scheduled to be sentenced in January.