From what I understand, Israel requested a pause to the hostilities (there's not exactly an official ceasefire in geopolitical terms as there are several necessary frameworks, procedures and agreements required that was not applied in this case) because alongside depletion of its air defense missiles, it was taking significant damage to key sectors of its economy: Haifa, the pivot point for EU to counter the East West corridor, was taking significant damage including it's oil refinery, its loss of commerce via its 3 ports, 1 of which is completely closed and a displacement of a significant number of it's citizens. Essentially the economy was beginning to shut down.

The bombardment Iran was inflicting on Israel would overrun Israel's ability to defend against it -- it's widely believed that Iran has large stockpiles of missiles well beyond Israel's capacity.

So rather than provide Israel with more munitions to an air defense that was proving to already be inefficient, the US stepped in with it's attack on Iran's nuclear sites... which we all know now was mostly theater