We are already seeing civilians killed: https://aje.news/p4rw7y?update=4345551 [Five killed in Israeli attack on elementary school in Iran]

It's the Iranian people who will be the final judge of how much civilian death is acceptable.

If so many Iranian civilians die that this new revolution fails, then not only will regular Iranians continue to suffer, but all the deaths in the protests and these bombings will have been completely pointless.

If few enough Iranians are affected that they persist, then it may well be worth it.