All terrorists see themselves a soldier in a just war against whoever their attacks are targeting.The rebels are not terrorists. They were soldiers in a just war against the Empire.
https://en.wikipedia.org/wiki/Rebel_Alliance
A lot of people treat being a fictional terrorist as automatically being a bad guy, but if the nation you are opposing is evil, then you can be a good guy terrorist. The Rebels in Star Wars, the New Caprica resistance in Battlestar Galactica ,and the Bajoran Resistan in DS9 are perfect examples of this.