"For the ways my work was used to divide people rather than bring us together, I ask forgiveness and I will work to do better," Zuckerberg said in the post.
He did not refer to specific issues in the message, which comes as Facebook and other technology companies are under increased scrutiny amid a US investigation into potential Russian involvement in the 2016 US Presidential election campaign.
Facebook said on September 6 it had found that an operation likely based in Russia spent $100,000 on thousands of US ads promoting divisive social and political messages in a two-year-period through May.
Facebook, the dominant social media network, said 3,000 ads and 470 "inauthentic" accounts and pages spread polarizing views on topics including immigration, race and gay rights.
Probes being conducted by several congressional committees along with the Department of Justice, have clouded US President Donald Trump's tenure since he took office in January and have threatened his agenda, which has yet to secure a major legislative victory.
(Reporting by Sinead Carew in New York; Editing by Sandra Maler)