The 34-year-old actress - whose directorial debut Lady Bird won a Golden Globe for Best Comedy/Musical on Sunday night - was asked whether men who have been accused of sexual assault can work again, and what the future holds for filmmakers such as as Allen or Roman Polanski.
Gerwig - who worked on Allen's 2012 movie To Rome With Love - told The New York Times: 'I would like to speak specifically to the Woody Allen question, which I have been asked about a couple of times recently.
'I can only speak for myself and what I've come to is this: If I had known then what I know now, I would not have acted in the film.'
The star also said she would not be working with the director in the future, before referencing Dylan Farrow, Allen's adopted daughter who accused Allen of sexually abusing her when she was seven-years-old in 1992.
Allen has never been found guilty of child sex abuse.
'Dylan Farrow's two different pieces made me realise that I increased another woman's pain, and I was heartbroken by that realisation,' Gerwig continued.
'I grew up on his movies, and they have informed me as an artist, and I cannot change that fact now, but I can make different decisions moving forward.'
Gerwig's comments come following the online backlash Justin Timberlake received for wearing a Time's Up badge at the Golden Globes due to his involvement in Allen's latest film.
The singer was accused of being a 'hypocrite' for wearing all black at the event, which was a request from the initiative to raise awareness for the campaign.
Meanwhile, it was recently announced that the Time's Up legal defence has reached its $15million goal. The money raised will provide legal support to women and men who have experienced sexual harassment, assault, or abuse in the workplace.
The initiative was launched in a bid to end sexual harassment in all workplaces.