Moore's comments came Saturday during his keynote speech at the Library of Michigan's 10th Annual Night for Notables -- an annual event to honor 20 books written by Michigan authors, The Detroit News reported.
During his speech, Moore reflected on a dispute he had with publisher Harper-Collins about his 2002 book "Stupid White Men." The publisher, he said, continued to delay the release of the book.
"They said, 'You can still be against Bush, but just tone it down!'" Moore said, adding the publisher threatened to toss out the 50,000 copies they had already printed if he did not change parts of the book.
Later, Moore said he was speaking in front of a union group and aired his grievance with the publisher. A librarian happened to be in his audience.
"She was on a librarian listserv [an early Web discussion group], and apparently she wrote a letter to the other librarians, telling them that Harper-Collins wouldn't publish the book, and here's why," Moore said.
"A few days later I got a call from my editor at Harper-Collins, screaming: 'What did you tell the librarians?' I said, 'I didn't tell the librarians anything!' 'Well they're out there picketing us. In Manhattan!'" the filmmaker said. "Essentially the publisher was afraid, because the message would be to other writers, if you sign with Harper-Collins, you're signing with a censor. You might not want to do that.
"Huge egg on their face," Moore said. "But the most important thing it did was to remind me that a single person can effect change. We should have a Rosa Parks holiday to tell people, don't just sit there, do something. We need to dispel the great lie that you can't do anything about things."