Most probably the engine mounts or something along the transmission. However, I think you need to hit a curb pretty bad, in order to break the mounts. I mean an impact where the tire and the alloy wheel would probably blow. Other wise, I climb curbs on a daily basis, due to parking issues and my mounts seem to be fine - plus it's a diesel, the "under pressure combustion" itself breaks the mounts on long term
Anyway, an inspection would surely reveal what's loose down there.