My guess would be that the argument goes something like, building A is a military target for X reasons (would have to produce intelligence of why it is and how the destruction of it is beneficial for Isreal militarily).
Building A is occupied largely with civilians so in order to bomb building A certain steps have to be taken to ensure the safety of as many civilians as possible (obviously you can not do this if you're a Putin or not a liberal democracy)
Said steps are taken (phone calls, warning shots, leaflet dropping, tannoy announcements etc etc) and you then bomb the building.