If it's based on, as I think it should be, on the chances for success and there's considered to be no chance of success—and success is not necessarily the establishment of a democratic government in a very western style—then no. Aiming at the latter doesn't work. However, if it stops the killing, then it certainly is justified.
The problem is that any attempt at the peace process doesn't include the most serious parts of the various insurgents who are operating with seven neighbours, of which at least three or four are safe havens for them, and the UN in particular is not permitted to cross the borders.
What's interesting is the presence of the United States Africa Command—and don't kid yourself, they're there—and the French, who are killing insurgents, and the new force of five African nations that's trying to figure out what it's supposed to be doing right now. None of them will accept direction from the UN. They will not come under UN control.