That's not inflicting casualties in and of itself. There have to be those additional factors, which aren't present here, since they are firing at the enemy forces, not at civilians for no reason. If a battle is happening in a populated area, some civilian casualties are unavoidable, and that is not a war crime.
Firing a mass casualty producing weapon that you CAN NOT EVEN AIM into the MIDDLE OF A CITY is a war crime.
And that is just what the “rebels” want to do - kill infidels, in this case they are Alawi, Kurdish or Christian. It doesn’t matter if they are military or not.
And obama supports them.