DiCaprio will instead take the part of an aging, out-of-work actor in the as-yet untitled movie being produced and directed by Oscar-winner Quentin Tarantino, Variety and Deadline.com said.
Plot details have not been released but Tarantino said in November that it was not a biographical movie but a story set during the summer of 1969, when a string of gruesome killings in Southern California were carried out by Manson’s followers.
Manson, one of the 20th century’s most notorious criminals, died in November at the age of 83. He had been serving a life sentence for ordering the murders of nine people including actress Sharon Tate.
The Sony Pictures movie is to be released on Aug. 9, 2019, exactly 50 years after Tate and four friends were stabbed or shot dead.
Deadline and Variety said that Australian actress Margot Robbie has been asked to play Sharon Tate. Tom Cruise, Brad Pitt and Al Pacino are also rumored to be interested, or are being sought, for the movie.
Sony Pictures, part of Sony Corp, did not return a request for comment on the casting.
The movie will be the first Tarantino film to be released without the Weinstein Company following allegations by more than 70 women of sexual misconduct against its former chief executive Harvey Weinstein.
Weinstein, who has denied having non-consensual sex with anyone, was fired last November and his independent production company is currently up for sale.
Reporting by Jill Serjeant; Editing by Lisa Shumaker