It might but it is unlikely, considering that a rocket is aimed to be most efficient. Deviating it from it's course should be enough to decrease the effect.

An exception to this might be that the rocket aims a city of thousands, who get sheltered successfully, which means the rocket would kill about zero people. When the rocket now gets deviated it might hit a target with hundred people who didn't get sheltered. Therefore the result for the population might be worse. My feeling (and I am definitely not an expert) is that this is comparatively unlikely, though.