He is currently serving a six-year sentence but maintains that he mistook Steenkamp for an intruder.
The release of the trailer has seen many South Africans taking to social media, with some calling it a "disgrace".
The Pistorius family have already said they plan to sue producers Lifetime, with Oscar's brother Carl telling the Cape Argus newspaper the family distances itself from the film.
"It was made with blatant disregard of both the Steenkamp and Pistorius families, as well as complete disregard for Reeva and Oscar. Neither Oscar, the defence, or the family were involved in the production of this 'film' in any way," Carl Pistorius said.
"The 'film' is not a true reflection of what happened on the day of this tragedy and the subsequent trial of the matter. It is a gross distortion of the findings of the court.
"The 'film' is a gross misrepresentation of the truth. The 'film' is rather a representation of what the prosecution tried to portray.
"We will be taking legal action."
Times Live reports Steenkamp's parents were "outraged" by the trailer.
The Steenkamps stressed they had not collaborated in the project or knew anything about it being made, and said they were still in mourning for their daughter.
"Any impression that is created that this is the view of June [Steenkamp's mother], or that the movie is endorsed by the Steenkamp family, is untrue and incorrect," the Steenkamp family said in a statement.