The message said the boys involved acted on a dare, which was filmed at a "private social event".
"The video was shared widely, causing great embarrassment to all involved. As you can imagine, this has been very distressing for the boys and their families."
The school's priority was the wellbeing of the pupils, and there were serious concerns around the impact of any news media coverage, social media sharing and "community gossip".
"We continue to hold concerns about the effects of sharing and discussing this short moment in the boys' young lives by their peers and the wider community."
The pupils had reflected on how they had conducted themselves, the principal said.
"We can all make mistakes, especially teenagers, but what is most important is how we learn from those mistakes.
"We all know the impact social media can have on young people, and of course, the glare of the news media spotlight can amplify any online discussion.
"There have been suggestions that a more public response could have come sooner, but we had to consider the immediate and serious concerns for the wellbeing of the boys and their families, so felt it was not appropriate before this."
The principal finished by saying they were available to meet any parents who had concerns, and that the school was working "extremely hard to deal with and move forward from this issue in a way that ensures the wellbeing of the boys involved".