The Twilight actor told Parade that he isn't confident enough in his wit to take on a humorous role.
"I don't know if I'm particularly funny," he said to the magazine.
He added of his comedy skills: "One of my legs is shorter than the other one, so that makes everything look really awkward. I can look like an idiot, but I don't know if I can be witty."
Pattinson's Bel Ami co-star Uma Thurman recently joked that the star lacks the "diamond-sparkle skin" his Twilight character Edward has in the vampire films.
Bel Ami opens on March 2 in the US and in the UK.
> Bel Ami set flooded with Robert Pattinson fans in Budapest
> Kristen Stewart buys Robert Pattinson vintage guitars for Christmas
Watch the trailer for Bel Ami below: