Right now, I don't know. There are a few options I can think of, but nothing is concrete.
1) The drone operator and/or his superior/team went rogue and intentionally targeted aid workers in order to starve Palestinians
2) The drone operator didn't go rogue and was following IDF policy to target aid workers in order to starve Palestinians
3) Israeli military chief cites 'misidentification' for strikes killing aid workers
Israel's military chief, Lt. General Herzi Halevi, announced the results of a preliminary investigation early Wednesday.
“It was a mistake that followed a misidentification“ at night during a war in very complex conditions. It shouldn’t have happened,” he said.
So now you, why do you think Israeli officials including Netanyahu are expressing regret if they meant to do this, and don't care about world opinion?