As others have commented it's not typical for people (or philosophers) to consider all violence unjustified, or even all non-state sanctioned violence as unjustified given that the state could be unjust and "an unjust law is no law at all" (MLK). If "those who make peaceful revolution impossible will make violent revolution inevitable" (JFK) then presumably given intransigent injustice violence in the cause of freedom may be not merely permissible but praiseworthy or heroic.

Not only is it not typical for people to regard violence as categorically unjustifiable, to suppose all violence unjustifiable is arguably incoherent. What constitutes violence? Some might entomb others alive without laying a hand on them, literally or metaphorically. If conceptions of what constitutes violence are restricted to the physical and all violence is regarded as unjustified those being buried alive would be at the mercy of those doing the burying. For example a land locked country dependent on food imports to feed it's population could be denied trade by it's neighbors and starved. And yet legally foreign countries are usually regarded as having the right to close their borders to unwanted stuff. On the one hand it seems clear that should surrounding countries decide to starve out their land-locked neighbor it's these surrounding countries that are in the wrong but on the face of it they'd be within their rights to so insist. Should those being starved out resort to violence or war, who would have drawn the proverbial first blood?