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.
You also may be giving too much credit to Hamas and Islamic Jihad's ability to aim rockets at the intended targets. Plenty of the time they hit the middle of nowhere, or they've actually even hit Palestinian-dominated areas (Hebron and Bethlehem) [1][2]
In many situations, it makes far more sense to save the Iron Dome counter-missles.
I dont think that the rockets are aimed to be most efficient but you could make the same argument by saying that the rockets are only intercepted if the iron dome system thinks they will hit a densely populated area.
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.