The Two and a Half Men actor wrote about the ousted Penn State football coach Joe Paterno, who was fired from the university amid his former assistant Jerry Sandusky's child abuse scandal.
Sandusky is alleged to have sexually abused eight boys over a 15-year period. Paterno reported the claims of abuse to Penn State's athletic director, but has been criticised for not taking more action.
Kutcher protested Paterno's firing, writing in a now deleted post: "How do you fire Jo Pa? insult. no class. as a [University of Iowa] hawkeye fan I find it in poor taste."
When Kutcher's remarks were condemned by a number of his Twitter followers, the actor apologised and said that he planned to stop posting on the social networking website.
He tweeted: "As an advocate in the fight against child sexual exploitation, I could not be more remorseful for all involved in the Penn St. case.
"As of immediately I will stop tweeting until I find a way to properly manage this feed. I feel awful about this error. Won't happen again."
Kutcher has made headlines recently over rumours that his marriage to Demi Moore is in trouble.
A young woman named Sara Leal has claimed she was seduced by the actor on the night of Moore and Kutcher's sixth wedding anniversary, but the Two and a Half Men star recently called on his fans to be skeptical about what is reported in the press.
> Demi Moore accused of attacking photographer
> Demi Moore, Ashton Kutcher 'act like couple on Two and a Half Men set'
Watch Ashton Kutcher in the trailer for New Year's Eve, which opens on Decemer 8 in the UK and on December 9 in the US, below: