I think the important thing to keep in mind is that it's an action of last resort anyway. Nobody uses violence before exhausting peaceful avenues. People do not turn to revolution until they are utterly convinced other options are non existent, and among the average person it takes an awful lot to bring someone to that point.

We communists would very happily take a peaceful transition of power out of the hands of the bourgeoisie and into the hands of the working class. We're just not stupid or naive enough to believe that they will ever allow that to happen, at the point of us actually coming close to achieving that they would unleash unspeakable violence on everyone. We are simply aware of that and intend to be prepared for it. The act of revolution by the masses, the whole masses, is an action of self defence, at least from the perspective of the population.

Coups on the other hand are a quite different beast.

There's a few different political ways of approaching the issue of mass death of innocents during revolutions but if you need to justify it in a moral sense, I think Mark Twain's quote here is very good:

“There were two “Reigns of Terror,” if we would but remember it and consider it; the one wrought murder in hot passion, the other in heartless cold blood; the one lasted mere months, the other had lasted a thousand years; the one inflicted death upon ten thousand persons, the other upon a hundred millions; but our shudders are all for the “horrors” of the minor Terror, the momentary Terror, so to speak; whereas, what is the horror of swift death by the axe, compared with lifelong death from hunger, cold, insult, cruelty, and heart-break? What is swift death by lightning compared with death by slow fire at the stake? A city cemetery could contain the coffins filled by that brief Terror which we have all been so diligently taught to shiver at and mourn over; but all France could hardly contain the coffins filled by that older and real Terror—that unspeakably bitter and awful Terror which none of us has been taught to see in its vastness or pity as it deserves.”

When events like what is happening in Gaza are going on, we aren't talking about going from a peaceful, prosperous society and upending it in a tsunami of violence for the sake of constructing something, hopefully, even better. We are talking about a situation that might have been relatively peaceful but in which many, many people are suffering and dying under oppressive structures on a day-to-day basis. The "passive" level of suffering and misery in these places, over the span of years and decades, is so much higher than whatever pain a successful revolution could create.

In that sense, revolutions like in Palestine aren't starting violence - they are ending it. And as such should generally be praised instead of condemned.

Killing civilians to make a point is stupid, all it does is make you look like a threat to the people who's support you need. (unless you are some sort of racial/religious supremist where killing demonstrates commitment to those ideals)

During a socialist coup civilians shouldn't ever be targeted. Its counter productive as the new government wants to have popular support. Once the government and military are under control of the socialists, then some civilians may cross the line into counter revolutionary criminals and some of them deserve to die if they fail reeducation.

israeli settlers were not civilians they were living on occupied land in illegal settlements in breach of international law. They decided to move into a war zone, often even evicting Palestinians from their homes and moving in.

9/11 victims were civilians but OBL was retaliating for USA's mass murder of civilians. That doesn't make it right but it means USA bears much of the responsibility.

Oil executives aren't civilians in the context of ecologic politics. Politicians are obviously not civilians. Billionaires not civilians. Management for international resource extraction (like a Canadian working for Rio Tinto in Africa or South America) are not civilians as they are actively participating in neo-colonialism.

You also have ira, 17n, raf, basque whatever its called army. Relatively minimal civilian casualties, absolutely molding states and kinda tacit support from the population.

Civil wars are results not of bloodthirstiness, but of previous regimes not wanting to give up power. You dont just decide "we want a civil war" or "if we don't get a civil war we failed", you just get it due to unevenness of happenings either geographically or military hardware-wise

There's a whole lot of writing and theory about just war and avoiding civilian casualties and right to revolution, but no one has ever followed any of that shit. In the end it just comes down to how bad you want to win, what your goals are, and what you're willing to sacrifice.