I don't know if you can exclude object from light (i guess you can) ....
But for a night scene, just put a dark blue/grey in the ambient color, and only add lights with attenuation where you need some (headlights, lights on the bridge or along the road, etc.. )
You can also try to desaturate a bit your final render in post-production because humans don't see colors very well in the dark (the best is to make a matte with general luminosity to desaturate only where there is no lights, as in reality, but it's more work lol).. It's a simple but effective tips to get better a night ambience.