Siblings Prince Albert II, Princess Caroline and Princess Stephanie, joined other members of their family to officialy give their opinion on the film, which is based on the life of Hollywood star-turned-princess Grace Kelly — who Albert, Caroline and Stephanie's mother.
The film centres around Grace's life after she married Prince Ranier and retired from acting and shows the dilemma Grace faced when Alfred Hitchcock, offered her a part in his film Marnie.
"On the occasion of the upcoming screening of the film Grace of Monaco at the opening of the Cannes Festival on May 14 2014 and its release in theaters, the Prince's Palace would like to reiterate that this feature cannot under any circumstances be classified as a biopic," read a press release from the palace.
According to the royals the film's trailer "appears to be a farce and confirms the totally fictional nature of this film.
"It reinforces the certainty, left after reading the script, that this production, a page of the Principality's history, is based on erroneous and dubious historical references.
The Monegasque royals also referenced changes they tried to make while the movie was in production, that they feel were consequently ignored by the team.
"The director and producers refused to take into consideration the many observations made by the Palace because these called into question the entire script and the characters of the film.
"The Princely family does not in any way wish to be associated with this film which reflects no reality and regrets that its history has been misappropriated for purely commercial purposes."
Responding to previous criticism, director Olivier Dahan and screen-star Nicole Kidman have previously clarified that the film is not a biopic.
"This is not a biopic or a fictionalized documentary of Grace Kelly," said Nicole. "But only a small part of her life where she reveals her great humanity as well as her fears, and weaknesses."
"I am not a journalist or historian," added Olivier. "I am an artist. I have not made a biopic. I have done, in any subjectivity, a human portrait of a modern woman who wants to reconcile her family, her husband, her career. But who will give up her career and invent another role. And it will be painful.
"I understand their point of view," Olivier said of Albert, Caroline and Stephanie's criticism. "After all, it is their mother. I do not want to provoke anyone. Only to say that it's cinema."