Justin Bieber -- I'm Sorry For My Racist Joke

Justin Bieber is apologizing for telling a racist joke when he was 15 ... blaming it partly on his age.

Justin tells TMZ, "As a kid, I didn't understand the power of certain words and how they can hurt. I thought it was ok to repeat hurtful words and jokes, but didn't realize at the time that it wasn't funny and that in fact my actions were continuing the ignorance."

Justin goes on, "Thanks to friends and family I learned from my mistakes and grew up and apologized for those wrongs. Now that these mistakes from the past have become public I need to apologize again to all those I have offended."

Justin continues, "I'm very sorry. I take my friendships with people of all cultures very seriously and I apologize for offending or hurting anyone with my childish and inexcusable mistake. I was a kid then and I am a man now who knows my responsibility to the world and to not make that mistake again."

And Justin says, "Ignorance has no place in our society and I hope the sharing of my faults can prevent others from making the same mistake in the future. I thought long and hard about what I wanted to say but telling the truth is always what's right."

Justin ends with this: "Five years ago I made a reckless and immature mistake and I'm grateful to those close to me who helped me learn those lessons as a young man. Once again....I'm sorry."