The prince and his sisters Princess Caroline and Princess Stephanie, said that "numerous requests for changes" had been ignored and that the screenplay "had caused much astonishment".
"There-fore, the royal family wishes to stress that this film in no way constitutes a biopic," said the palace's statement.
"It recounts one rewritten and needlessly glamorised page in the history of Monaco and its family with both major historical inaccuracies and a series of purely fictional scenes."
The American-born actress was one of the world's most famous film stars when she married Rainier III Prince of Monaco in 1956, becoming Princess Grace of Monaco.
Princess Grace died in a car crash in 1982, at the age of 52, following a stroke while driving.
The film is said to portray how she supported Rainier during tense negot-iations that led to a new consti-tution.
In an interview with 'Le Figaro', Kidman said the film was a dramatic work charting Kelly's " path from cinema to royalty".
"This is not a biopic or a fictionalised documentary . . . but only a small part of her life where she reveals her great humanity as well as her fears and weaknesses," she said. (© Daily Telegraph, London)