Producer Effie Brown has said if people of colour and women want to boost diversity in Hollywood they need to take action, rather than be complicit.
Brown, who clashed with Matt Damon over comments he made on diversity last year, said: "Somehow, we co-signed this. Somehow, we participated."
She said if those who want to change the situation in Hollywood were not taking action, they were supporting it.
It comes amid a row on the lack of diversity in the Oscar nominations.
All of the nominees in the four acting categories - for best actor, best actress, best supporting actor and best supporting actress - are white this year.
This prompted director Spike Lee, actress Jada Pinkett Smith and her husband Will Smith to announce they would not be attending next month's awards, as well as #oscarsowhite trending on Twitter.
On Monday, Variety co-editor-in-chief Claudia Eller tweeted a picture of its latest cover, featuring a white Oscar and the words "Shame on us".
She wrote: "Tomorrow's cover on diversity crisis will be a must-read. As the cover line states, we are all to blame. Let's act!"
Speaking at a Sundance Film Festival event for women, Brown urged all of those present to "hire, mentor and invest" in women and people of colour.
'Explore blind spots'
Damon was criticised last year for comments he made on his Project Greenlight show about who should direct a film being discussed, featuring a sole black character, who was a prostitute.
When Brown, producer of critically-acclaimed film Dear White People, suggested the director would have to be chosen carefully in order to handle the character, Damon responded that diversity is "what you do in the casting of the movie".
His comments led to the coining of the term "Damonsplaining", with one social media user describing it as "over talking and/or shouting down a person of colour to explain something about their own race or culture".
Speaking at the Women at Sundance brunch, Brown asked those attending to explore their own "blind spots".
"Women make up half the population and people of colour make up 40%,'' she said. "There is no such thing as innocent bystanding any more.
"Our voice is powerful. We are a force of nature."
Pitch Perfect 2 director Elizabeth Banks agreed with Brown's comments, saying: "We are up against something, which is the entirety of human history."
Jacki Zehner, a member of the Sundance Institute board of trustees, told those at the event they should "vote with their wallet" to support films made by, and about, women and people of colour.
Damon later apologised to anyone offended by his comments on Project Greenlight, but added that what he said was "part of a much broader conversation".
The actor, nominated for an Oscar for his role in The Martian, has welcomed pledges made by the Academy, the organisation behind the Oscars, to double the number of its female and minority members.
But he said it was a "a wonderful first step" but that Hollywood still needed to do "much, much, much more" to reflect society.
It has been announced that three new seats will be added to the Academy's board of governors to improve diversity in leadership.
Under the new rules, voting rights will only be given to those who have been active in the industry in the past decade, have been nominated for an Oscar, or have worked in the industry during three separate 10-year periods.
"The Academy is going to lead and not wait for the industry to catch up," Cheryl Boone Isaacs said in a statement.
The Academy has published a list of answers to questions arising over their new voting rules.