The actress - who stars as Pepper Potts in the Iron Man films - said that she was getting too old for action movie roles.
"I just came off of Iron Man 3, which is as special effects-y and action-y as it gets," she told E! News. "So to do something like [Thanks For Sharing] where it's really small, funny and exciting, is really great.
"I don't know [about returning for The Avengers sequel], I'm getting old for this s**t, you know what I mean?"
Paltrow briefly reprised her role as Potts in Joss Whedon's first Avengers movie.
Co-star Robert Downey Jr is said to have insisted that the actress join him in the superhero ensemble movie.