Bleeding Cool claims to have heard from an "untested, unknown source" that the star let the casting decision slip during a Hollywood party.
Johnson's Journey 2: The Mysterious Island director Brad Peyton was hired to helm Lobo last month, prompting rumours that the duo could reunite for the comic book project.
Guy Ritchie was previously attached to the movie, but instead opted to film Sherlock Holmes: A Game of Shadows. Producers Joel Silver and Akiva Goldsman remain on board.
Lobo, an interstellar mercenary and bounty hunter, was created by Roger Slifer and Keith Giffen in 1983. The character went on to guest star in numerous DC publications, and feature in several solo titles.
Warner Bros is yet to announce a release date for the Lobo movie.
Watch Dwayne Johnson discuss The Fast and the Furious 6 with Digital Spy below: