You don't need to have a Star Destroyer descending on the city...that's killing a fly with a sledgehammer.
Have some TIEs and that Imperial Landing Craft that they added to the Sandtrooper scenes in ANH coming in and start shooting buildings and such, maybe have some just pass by a window, lasers firing, but we don't need to see what they're shooting. Just create the sense that "the Empire has taken control of the city", as Lando just announced.