Responding to Trump's tweet labeling the leading social network platform "anti-Trump", the Facebook CEO and founder said the social media platform had tried to be neutral in the US elections.
He, however, said, he regretted dismissing concerns about the Facebooks role in influencing the US presidential race.
"Every day I work to bring people together and build a community for everyone. We hope to give all people a voice and create a platform for all ideas," he said on his Facebook page.
Days after Facebook agreed to cooperate with Congress on its investigation of Russian meddling in the 2016 election, President Trump criticised the social network for being "anti-Trump".
More From This Section
Trump tweeted: "Facebook was always anti-Trump.The Networks were always anti-Trump hence,Fake News, @nytimes (apologized) & @wapo were anti-Trump. Collusion?"
Facebook has said last week that it would provide the contents of 3,000 ads bought by a Russian agency to congressional investigators and make political advertising on its platform more transparent.
In his long Facebook note, Zuckerberg expressed regret for saying after the election that it was a "crazy idea" that fake news disseminated on Facebook influenced the election.
After the election, I made a comment that I thought the idea misinformation on Facebook changed the outcome of the election was a crazy idea. Calling that crazy was dismissive and I regret it," he wrote.
"This is too important an issue to be dismissive. he said.
He said that Facebook's biggest role in the US election was as a platform for candidates and citizens to communicated directly with one another regarding issues.
"There were billions of interactions discussing the issues that may have never happened offline. Every topic was discussed, not just what the media covered," he asserted.
"This was the first US election where the internet was a primary way candidates communicated. Every candidate had a Facebook page to communicate directly with tens of millions of followers every day. Campaigns spent hundreds of millions advertising online to get their messages out even further. That's 1000x more than any problematic ads we've found, he said.
"We will continue to work to build a community for all people. We will do our part to defend against nation states attempting to spread misinformation and subvert elections," said the Facebook founder.