The user, part of the Reddit online community, said they did not intend to incite violence against members of the media. The video, in which the president tackles a man with the CNN logo superimposed over his head to the ground and punches him several times, went viral in late June.
It first appeared on an alt-right forum on Reddit, before being tweeted by Mr Trump himself days later.
It was the latest move in an ongoing feud between the US leader and the media, with CNN issuing a statement criticising the video as condoning aggressive behaviour toward reporters.
The user’s apology was quickly removed, but a screenshot has been posted on social media.
In it, the account holder said they “never meant any of the hateful things I said in those posts”, and that they are “not the person that the media portrays me to be in real life”.
They said their main aim was to provoke a reaction, but that “trolling to get a reaction out of people is not the best way to make a point”.
“Just because you are behind a keyboard doesn’t mean you can’t hurt someone with your words or cause a situation such as this one where a simple meme is misconstrued as calling for violence”, they said.
The user also went on to apologise for other racist and anti-Semitic posts, and said he wouldn’t be posting “hurtful or hateful things in jest online”.
it has spoken to the person behind the account which posted the video, and reserves the right to publicly release their identity if they go against their apology.
- with wires