The 71-year-old actor, famous for playing Del Boy in the classic BBC sitcom, believes that the original London setting is intrinsic to its success.
"They can do brilliant comedy [in America] but I don't see that they can bring off Fools and Horses," he told BBC News.
"I don't see that it will travel across the pond. It might work but you've got to change it so much that, in the change, in order to Americanise it, do you lose the whole concept of the piece?"
Jason went on: "The language will have to change so much and there will be so many parts of the storyline you have to change.
"It's so London and so British, [in] its humour, that you wonder. It's London based and it took quite a long time for the rest of the country to catch up with the phrases.
"I have no idea what the American equivalent of 'plonker' is, for example. Or 'dipstick'."
Scrubs writers Steven Cragg and Brian Bradley are said to be adapting the show for US network ABC.
Asked who he would like to take his role, the star tipped Johnny Depp, adding: "You would never get him because he's too big but I'd go for Johnny Depp because he's such a good actor."
News of the US spinoff comes nearly a year after John Sullivan's death at the age of 64. The Fools and Horses creator and writer had been suffering from viral pneumonia.
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Watch a classic clip of Only Fools and Horses below: