Rourke, who used to be a professional fighter, maintains there is no way the Hollywood stars would stand a chance against serious opposition - despite training as boxers for their roles in Ali and Cinderella Man.
The 49-year-old actor is particularly scathing about Smith's assertion he could last a round with retired heavyweight world champion Lennox Lewis.
He says, "No f**king way. Lennox Lewis is a friend of mine, he couldn't last.
"When actors say they could be professional fighters they're full of crap. With a capital K."