The Republican National Committee had voted to block CNN from hosting GOP presidential primary debates in 2016 because of the project. Ferguson said that Democrats also didn't want him to make the film.
Ferguson wrote that Clinton media representatives "interrogated" him and people at CNN about it. He said one Clinton representative refused to speak to him but publicly questioned whether Ferguson would have a conflict of interest because it was a for-profit venture.
He said that "nobody, and I mean nobody, was interested in helping me make this film. Not Republicans, not Democrats — and certainly nobody who works with the Clintons, wants access to the Clintons, or dreams of a position in a Hillary Clinton administration."
"It's a victory for the Clintons, and for the money machines that both political parties have now become," wrote Ferguson, who declined a request to be interviewed through his management office. "But I don't think that it's a victory for the media, or the American people. I still believe that Mrs. Clinton has many virtues including great intelligence, fortitude and a deep commitment to bettering the lives of women and children worldwide. But this is not her finest hour."
Asked for comment on Ferguson's decision, Clinton spokesman Nick Merrill said, "lights, camera, no reaction."
The documentary was one of two projects on the former first lady and secretary of state announced this year. NBC Entertainment said it was planning a four-hour Clinton miniseries starring Diane Lane.
The Republican National Committee is pleased with the decision, spokesman Sean Spicer said. The committee is still discussing how many debates it wants to hold in 2016.
"We're particularly thankful to the grassroots that joined in our call to stop this project that was getting in the way of the electoral process," Spicer said. "Now the pressure is, frankly, on NBC."
Ferguson and David Brock, founder of the liberal media advocacy group Media Matters for America, also took shots at each other. Contrary to the Republicans, who worried about the publicity the documentary would give to a potential presidential opponent, Brock said he believed that Ferguson had an anti-Clinton bias.