The British theatre producer, who produced the long-running stage musical and the Bafta-nominated film, blasted the American Idol singer for his "naive and silly comment".
"What does he know about musical theatre? It was a naive and silly comment. He's an idiot," he said.
Former American Idol contestant Adam blasted the makers of the big screen adaptation on Twitter for casting Hollywood stars such as Hugh Jackman, Russell Crowe and Anne Hathaway instead of professional singers, and said vocals should have been recorded in a studio rather than performed live.
Cameron explained: "Good singers could not have given these performances on screen. The camera is cruel - you can get away with much more on stage than you can in the cinema. That's one of the reasons why Alain Boublil and I were so keen to remake our show as a film, rather than try to film our show."
"A lot of the fans of the show love the film. One of the main reasons is because they get more detail into the storytelling than is inherent in the show because of the exploration and the direction of Tom Hooper. Also, 95 per cent of the people in the film have come from musical theatre," he added.
Director Tom said: "I got the impression that he was quite surprised about his comments becoming a global story. I very much wanted to record live to allow the vocals to remain in a raw state... which embrace imperfection and let the emotions in."