I remember this from some thin comic from the 80s, possibly before The Empire Strikes Back came out.
The artstyle was European-ish (Adamov? Moebius?) and the subject was Luke and Leia (both inexplicably in still in their A New Hope outfits; do princesses ever change out of their ambassadorial gowns? do sand peasants change their keikogi?) on a Tantive-IV style ship encounter a wandering alien's vessel in deep space (actually this should not be that surprising in the Star Wars universe).
They are taken aboard. A pursuing Star Destroyer looking for aggro and considering everything not Imperial as something that needs to be destroyed engages in pointless hostilities and is removed immediately by the alien using antimatter blobs. Luke and Leia are sent back to their ship, and the alien departs, Galactica-style. The End!