About 8.8% of the French population is Muslim - it's not that small a minority. For comparison's sake, about 5.6% of America's population is Asian.
I don't condone the violence at all. But the fact that I don't condone the violence does not stop people from reacting violently when someone else *deliberately* does that which is deeply offensive to them.
Try walking down the street in Compton yelling the n-word and see what happens. Afterwards, most people would look at you (if you're lucky enough to wake up in the hospital) and tell you how stupid you were being.
The *same* principle applies to doing that which is equally deeply offensive to Muslims.
Using the n-word towards Blacks is legal, but is also rude, hurtful, and contributes to social disorder. The SAME understanding should apply to cartoons of Mohammed.