In a lengthy note posted on Facebook on Friday, the filmmaker said he wasn't aware of Weinstein's "repugnant and abhorrent behaviour" but would have intervened if he had, reports thewrap.com.
"Harvey Weinstein knew better than to behave inappropriately toward women in my presence," Moore wrote.
"I'm guessing successful sociopaths like him who get away with it for years are very, very careful not to let the kind of men who would stop them dead cold ever get a glimpse of who they really are."
Weinstein's companies have released several of Moore's films, including the upcoming Donald Trump documentary "Fahrenheit 11/9".
Moore said the revelations about Weinstein mark a "profound cultural/social/political moment" that he hoped will lead to the eventual collapse of "the white male hierarchy which has ruled our way of life in America since the first boatload of religious zealots arrived on Plymouth Rock".
"Let's use this moment to end the abuse of women in our industry," he wrote, reports thewrap.com.
"Let's make this a call for men to take a stand against the men who perpetrate this corrosive, criminal behaviour, to call them out and shut them down. We can do this. All it takes is the will and the decision to say ‘enough is enough!'"
Last week, The New York Times published a report detailing three decades of sexual misconduct, including accusations that Weinstein propositioned actresses and harassed female employees.
A number of other women have since come forward to accuse Weinstein of harassment or assault, including actresses Gwyneth Paltrow, Angelina Jolie, Kate Beckinsale and Cara Delevingne.
Dozens of stars and former collaborators have publicly condemned Weinstein in the wake of the allegations, including George Clooney, Meryl Streep, Cate Blanchett, Judi Dench, Mark Ruffalo and Nicole Kidman.
"I want to point out that there is also a fundamental fix that must occur in the long run if there is ever to be any real change," Moore wrote.
"We must reform our broken economic system and transform it into one that is equitable and democratic, one where the gap between rich and poor is eliminated so that no longer do a few wealthy men hold the power."