Speaking to Collider, Matt Smith seemingly ruled out his involvement with the rumoured Doctor Who movie.

When asked "Will you ever do a big screen Doctor Who movie?" Smith replied:

"I don’t know. There’s talk of it. I think David Yates was attached to do something. For my money, whoever is playing The Doctor should be in the movie. I don’t think there should be two Doctors. I think it would take four or five years to get something like that off the ground, and I don’t anticipate that I’ll be playing the Doctor then. My skin and the aging process couldn’t take it. But, I don’t see any reason why it couldn’t work. I think they should get Steven to write it because he’s the best."

[Source: Collider]