American ProCricket (APC) had announced on Thursday that Stewart and Caddick would be taking part in the inaugural professional league that will involve local teams from eight different cities.
However, Stewart said that he had never even heard of the new league.
"Don't believe everything you read," said the 41-year-old former England skipper and wicketkeeper.
Stewart played his last Test match -- an English record 133rd -- at The Oval in September 2003 where he helped England to victory over South Africa.
The former Surrey batsman ended his successful Test career as England's second highest run scorer behind Graham Gooch with a tally of 8,463 runs at an average of 39.54.
"I was unaware such a league existed and I was going to join," Stewart added.
England fast bowler Caddick was equally vague about his participation in the new American league.
And Somerset County cricket club confirmed that Caddick would not be playing in the US, and that he had no idea he had been touted to play in the first place.
The new tournament is scheduled to begin on July 2, when the New York Storm take on Florida Thunder.