Israel is dropping leaflets in Gaza warning residents of impending attacks. We never issued any sort of warning when we dropped firebombs and nukes on Japan.
It seems we made an attempt to drop leaflets warning the Japanese population of impending bombing, but they didn't go to the two cities that ended up getting the atom bomb. cf. Warning Leaflets In any case, the second bomb was supposed to be dropped on Kokura, with Nagasaki an afterthought due to the inclement weather.
The Israelis always bend over backwards to follow international law, and beyond.
We dropped warnings on Hiroshima. Not sure about Nagasaki.