Cowell claimed that he was "pissed off" with NBC for moving their singing talent show's third episode and described it as a "spoiling tactic".
"I think it is mean-spirited and I hope and I pray it backfires on them," Cowell told reporters.
"I am pissed off about it, because I think there's a kind of gentleman's agreement.
"But we have to rely that the viewers will make the right selection."
Talking about the fact former Disney stars Britney Spears and Christina Aguilera will now go head-to-head on the rival shows, he said: "Britney's not going to appreciate the fact that Christina - who has been a bit of a rival - isn't allowing Britney to have a night of her own.
"She's going to be devastated because she has put her heart and soul into this."
Cowell has revamped X Factor USA over the past 12 months after an underwhelming first season, which didn't get close to American Idol-sized figures in the ratings. Judges Paula Abdul and Nicole Scherzinger were ditched, along with British host Steve Jones.
Spears and Demi Lovato have joined as judges alongside Cowell and LA Reid, but no host has been found for the show, despite it launching next week.
Cowell was in the UK earlier this week, making editing adjustments to the UK X Factor, following a drop in ratings for the ITV1 series.