Last week the player, who represented Wales in the 2010 Six Nations described a Big Brother contestant as a “faggot”.
In a statement Phillips said: “I would like to apologise to anyone who may have been offended by the tweet in question.
“It was a stupid, throwaway comment that I made at the spur of the moment and no offence was intended whatsoever.”
Phillips added that with hindsight he realised the level of offence that the comment could have caused.
He said: “This incident has certainly taught me a lesson in how I conduct myself, and I have learnt the hard way to think before I tweet.
“I would like to reassure people that it won’t happen again.”
In a statement released by the Ospreys club, they said: “As a result of the investigation, we are able to confirm that Kristian Phillips did post a tweet on November 7 via his personal account containing terminology likely to be construed as homophobic.
“Having discussed the issue at length with the individual concerned, and taking into account all the available evidence, we are satisfied that it was an innocent, if extremely naïve comment to make, which was not meant in a homophobic way and no offence was actually intended.
“Kristian has also shown genuine remorse and regret for his actions and for any offence caused.”
Ospreys rugby club have said they do not condone his language in anyway and that their players must ensure that they are aware of their position in society as role models.
Ospreys added: “As such, Kristian will now face a financial penalty as per our internal disciplinary procedures, and we have reminded all employees of our social media guidelines to ensure that there is no repeat of this incident.”
It is not known what the amount of the fine was.