Defense of the innocent

Is it ever acceptable to speak up on behalf of those who are not able defend themselves against ignorant people? I find I have a very low tolerance for this sort of thing and I usually end up in a confrontation because of it. It inflames my anger, so I know that I need to transform the impressions and handle it better at least. It causes me to fall into criticism and all sorts of hypocrisy. This is obviously a product of my degenerated nature. I don't need the negative Karma obviously, but how do you bring this sort of thing to someone's attention without victimizing them.