The director has said that reports that Zachary Levi and Jim Sturgess are competing for the lead role of Star-Lord are "completely inaccurate".
"Almost everything in that Variety article on the Guardians of the Galaxy casting (and all the following articles based on it) was/is completely inaccurate," wrote Gunn in a message on his Facebook page.
"Just for the record."
The post appears to have since been removed, but was reported by ComicBook.com.
Eight actors were previously reported to be auditioning for the role of the half-human half-alien hero, including Joel Edgerton, Garrett Hedlund, Jack Huston, James Marsden, Lee Pace, Eddie Redmayne, Sturgess and Sullivan Stapleton.
Levi is currently filming Thor: The Dark World, in which he will play Fandral after the departure of Josh Dallas.
Marvel Studios' Guardians of the Galaxy is scheduled for release on August 1, 2014.