The moviemaker met with a string of stars including Tyrese Gibson, Terrence Howard, Chris Tucker and Michael K. Williams before casting Jamie Foxx in the main role as a slave in his western.
Tarantino admits The Wire star Elba was also in the running, but he ruled out the Brit as he didn't want any "phoney accents" in the film.
He tells Britain's The Sun, "Yeah, Idris is British and this is an American story.
"I think a problem with a lot of movies that deal with this issue is they cast British actors to play the southerners and it goes a long way to distancing the movie. They put on their gargoyle masks and they do their phoney accents and you are not telling an American story any more.
"They are just making hay of it, whether it be James Mason in Mandingo or Michael Caine in Hurry Sundown, they get British actors to do this."
With the exception of Leonardo DiCaprio, who plays a plantation owner in the drama, Tarantino's cast was almost entirely made up of stars from southern states.
He adds, "Leo is not from the south, but pretty much every other white actor in the movie is from the south. And most of the black actors are from the south. And I'm from the south."