I don't want to do a martial art to learn to fight, I'm a staunch pacifist but to helpe get in to better shape, aikido uses the minimal amount if effort for the maximum result, so I don't think it's for me
I agree with Awaken375 that Aikido would probably be good My brother is a pacifist like yourself and he did some training in this art I believe. Myself I practice Wado Ryu Karate, I can assure you I am not into violence, any martial artist would agree that martial arts is not about that at all. Having said this Martial arts by the very name are about fighting and defense.
I think Tai Chi may suit you this is a form of Martial art. This will give you great flexibility.. But k
I would urge you to try a local martial arts class. just pick one and give it a go. If iit doesn't fit with your moral beliefs you still have lost nothing. I think you will find it's not about mindless violence at all