Iran is in a difficult situation because on one hand -- it was attacked by Israel in a aggression targeting its embassy in Syria which triggered exchange of blows between the two nations. On other hand, maybe some in Iran are thinking to check Israel as well, in relation to numerous conflicts in region taking place against its allies. And it may factor in trying to restore some kind of balance in these arenas. Which makes it more ever difficult. If these arenas weren't active, it wouldn't need to respond decisively and in a immediate fashion.
Israel is trying to exploit the conflict in multiple arenas to threaten Iran as well which is why Iran is compelled to draw a line. But it may need to target Israeli infrastructure in next True Promise, if there is one.
Because US can quickly recompensate military losses or recoup costs for them. But for infrastructure, they are not going to do that. If they try to, it will take longer to recover losses.