"I like John, but he don't have what I have and the show sucks if he's on it. Sorry!" Sheen told TV's "Access Hollywood" in an interview to air Tuesday and Wednesday.
Stamos also tried to silence the buzz late last week via Twitter.
"contrary to the rumors, i am not replacing charlie sheen on two and half men. however, martin sheen has asked me to be his son," Stamos Tweeted.
CBS and Warner Bros. announced last week they were halting production indefinitely on "Two and a Half Men" after Sheen gave a rambling radio interview during which he repeatedly slammed show co-creator Chuck Lorre and talked up his own importance on the series.
Sheen has long battled addictions to drugs and alcohol, and his TV show was on hiatus when the actor gave his scathing radio interview. Until then, the show had been scheduled to resume production this week.
Sheen has said he intends to sue the producers for $300 million for breach of contract.
In a news release announcing the interview, "Access Hollywood" said Sheen also talks about his series co-star Jon Cryer "not having his back."
Cryer has not publicly commented on the current situation at work.