Anger in a dream can often represent other passionate emotions.
Aggression (an unprovoked attack) can be perceived as an extreme form of anger. We are struggling with the right to express that which is distressing us. We probably are unable to express emotion appropriately in waking life, but can do so in dreams.
Annoyance is a mild form of anger which is a reaction to a perceived threat.
It reflects our feeling that we are being denied what is ours by necessity or by right. Consult the entry for argue / arguments.