The star, who voiced Darth Vader in the original Star Wars trilogy, reportedly fell out with Lucas when the filmmaker used another actor when the iconic character was unmasked.
Prowse has also been accused of leaking plots relating to Vader's death, while the actor alleges he has not been paid a fair share of profit from the films.
The 75 year old, who has recently beaten pancreatic cancer, has been told he cannot attend any "Lucasfilm associated event", writing on his website, "The only thing I've been told is I've burnt too many bridges between Lucasfilm and myself."
Friends of Prowse tell Britain's The Sun he is being "punished", adding, "Dave never received much money for his role and was always shoved to the side. He believes he's been an embarrassment or annoying to Lucas. But he lives for conventions. So to strip this from him too is heartbreaking."