The Life on Mars actor was quoted earlier this week as saying that he is open to appearing in Doctor Who again to take The Master to a "very, very dark place".
"I'd love to have another take on him, to be a bit quieter," Simm told fans at the Cheltenham Literature Festival.
He also said: "I started annoying myself after a while [in my previous appearances]. [Then-showrunner] Russell T Davies had a specific idea of what he wanted him to be like. So I just had to do exactly what he wanted me to, and he wanted a giggling lunatic."
Simm has now taken to Twitter to clarify that he was speaking off the cuff and that another Doctor Who guest appearance is not actually in the works.
Simm first appeared in Doctor Who as The Master in the third series's three-part finale.
He returned for David Tennant's final episodes The End of Time, where The Master saved The Doctor's life by deflecting Time Lord President Rassilon's attack.
The character of The Master was originally played by Roger Delgado in 1971. Peter Pratt, Geoffrey Beevers, Anthony Ainley, Eric Roberts and Sir Derek Jacobi have also played the villainous Time Lord.
Doctor Who will return to BBC One this Christmas for a festive special, with eight more episodes to follow in 2013.
Watch John Simm in a Doctor Who clip below: