The actress told SFX that she had entered discussions with Buffy creator Joss Whedon about a new series featuring her character Faith.
"I met with Joss and [writer] Tim Minear and spoke about the potential for a Faith spinoff," she explained. "But Buffy had... gone on [for] seven years and Joss [said] he couldn't play the kind of day-to-day role he had on [that show]."
Dushku admitted that Whedon's decision impacted her own choice not to pursue the project.
"It wasn't that I felt... it wasn't right [without Joss] but it was a contributing factor," she said. "On top of it, I had just played this character for almost five years [and] it felt like time to explore a different role."
She added: "I ended up making a decision that... I don't regret, [although] in hindsight maybe the talks could have continued a bit longer."
The former Dollhouse star will make a guest appearance in the new season of The Big Bang Theory.