The tiger is the symbol of power, strength, aggressive behavior, grace and fast movement. If you were attacked by the tiger, then such dream means that you are feeling attacked by something in your waking life. The tiger is the symbol of bravery, so if you saw yourself being a tiger, it could mean that you have no fear or being very aggressive towards the others. The tiger sometimes shows the qualities of the person who is in unstable state of mind, after much stress or some situation in waking life.
Read more about dreaming of Tiger in other dream meanings interpretations.