It is possible you are thinking of "King Kong" (1976), which is a famous remake of the 1933 film. This movie has the following ratings and certificates:
* MPAA: PG (Parental Guidance Suggested) - for some frightening scenes.
* BBFC: 12 (Suitable for 12 year olds and above) - for mild threat and horror.
If you are referring to a different movie, please provide more details.