To dream that you are defending yourself suggests an underlying hurt. It may parallel a waking life situation where you are being put on the defensive.
To dream that you are defending someone indicates that you are projecting your beliefs and feelings onto someone else. By defending this person, you are deflecting or undermining your own beliefs. Perhaps you are not ready to confront your feelings.
Dreaming that someone is defending you or standing up for you symbolises your sense of self-worth.