Umm....you're talking about Dark Lord: Rise of Darth Vader
Well, as I see it, the Jedi are useless at the time being. Like at the moment, they can't really strike at the Empire and do significant damage. So, once they get more power they will be able to strike. So, since that rebellion will occur later, they have more significant worries to worry able at the time.
Later in the story Vader deals with them