"Which" is really important. The military just gunned down 40 members of the deposed Muslim Brotherhood - that's a very different thing than people being killed during a riot.
Liberals (and by that I mean everyone who favors establishment politics, republicans and democrats alike) like to get really post-modern about violence, as in "violence is always wrong no matter the who and the why" (unless it's the State's violence; which they're totally cool with) but not only is this approach Un-nuanced and illogical, it ignores the that's inherent in a given system.
If the material conditions are bad enough in a given place (such as Egypt) violence that is used towards ending those conditions can be understood, justified, or even preferable.
If you're the sort of person who says violence is always wrong no matter what, or violence exists in a vacuum, you yourself are behaving violently, by lending at the very least tacit support of those conditions that cause misery and death to billions.
The fact that a movement is violent, on it's own, says nothing about it's worthiness, it's the how and the why and the who that matter.