"I did it [already]," the actor told E! News at the G'Day USA Gala and AACTA International Awards. "I want to leave Danny the way he was. I don't even know what I would do in it if I did it."
Fox is set to air the live adaptation of the cult musical in January 2016, but hasn't yet revealed their Danny Zuko.
"Ryan Murphy and [co-producer] Nina Jacobson called and said they wanted to have dinner and discuss the possibility," Travolta told E! "I took a long time to decide, but I read the first three scripts and then I asked very important people in my life what they thought...and they all agreed that this was a good thing to do and I decided to do it. I have my work cut out for me."
Travolta recalled where he was when the verdict was read. "I was with my father, I believe, because he was obsessed with it because he was a big football fan," he said.