In 2019, Franco was sued by two former students of his acting and film school Studio 4 who claimed he had used his position to engage in “sexually charged behaviour towards female students”, including pushing female students into explicit sex scenes.
The 43-year-old's lawyers described the lawsuit as "scurrilous" and "publicity-seeking".
One of the ex-students, Sarah Tither-Kaplan, had previously spoken out in 2018. When the allegations first surfaced, Franco described them as "not accurate".
The suit was settled in February this year.
In a new interview with the Sunday Times, Rogen said: "What I can say is that I despise abuse and harassment, and I would never cover or conceal the actions of someone doing it, or knowingly put someone in a situation where they were around someone like that.”
Watch: Seth Rogen clears up 'false' rumour that Emma Watson stormed off set
Rogen, 39, added he regrets making a "terrible" joke during his Saturday Night Live hosting gig in 2014 where he jested he had posed as a young girl on Instagram to "prank" Franco, making light of a 17-year-old's allegation that the actor had messaged her to meet up.
He also reflected on a 2018 interview where he said he would continue to work with the 127 Hours star.
“I look back to that interview in 2018 where I comment that I would keep working with James, and the truth is that I have not and I do not plan to right now,” he said.
Rogen also said it had affected their relationship as he explained: “I can say it, um, you know, it has changed many things in our relationship and our dynamic.”
Franco and Rogen have collaborated on a number of projects in the past, including Sausage Party, The Interview and Pineapple Express.