Billy Murray - who plays Captain Price in the series - was reported to have told an Xbox fansite that he is working on the sequel, but now claims he was misquoted.
"I told the guy I was doing a special new Modern Warfare for China, not Modern Warfare 4,″ he wrote on Twitter.
"The guy I spoke to on the plane was very nice and I'm really pleased he loves the game but the facts have got a bit confused somewhere."
The game in question is believed to be Call of Duty Online, a free-to-play version of the military shooter aimed at the Chinese market.
Developer Infinity Ward previously downplayed the reports of Murray's involvement in Modern Warfare 4, but did not deny the existence of the game.
The next entry in the Call of Duty series, Black Ops 2, will be available on Xbox 360, PS3 and PC from November 13 worldwide, and Wii U from November 30 in Europe.
> 'Black Ops 2' multiplayer preview: Six anticipated new features
Watch a live-action trailer for Black Ops 2 below: