Cruise told Reuters Television at the world premiere in London of Jack Reacher that he would not have taken the part if British thriller writer Child had been unhappy.
Child's version of Reacher - a military sniper - is 6 foot 5 inches (almost 2m) tall and weighs over 200 pounds (91 kilograms). Cruise (50) is just 5 foot 7 inches (1. 7 meters) tall according to the Internet Movie Database, and has a trim physique.
"You know, he (Child) created the character, I had my own opinion that I didn't say to Lee and then he came back and pretty much reflected what I had felt about it. But had he said 'look, I'd rather not', I would not have played the character," Cruise said.
Cruise described Reacher's size as a "characteristic" rather than a "character."
Jack Reacher, to be released later this month, is based on One Shot - one of the series of best-selling novels by Child about the eponymous former soldier turned drifter who travels the United States dealing out his own brand of justice.
British actress Rosamund Pike, who plays the female lead, said she hoped there will be many more Reacher movies.
"We hope this is going to be a great big new franchise for Tom and for Paramount and so to be in the first one is always kind of cool ... It's witty, it's fast-moving, the plot is ... puzzling and incisive and quite dark in places.
"You know, the humour and the violence in this film is pretty edgy and I like that about it," Pike said.
Cruise was also a producer on the Paramount Pictures movie, which is due for release in the United States on December 21.
