what does it mean to see a three year old child smoking?

The dream might mean she is afraid of what the future will bring and needs to abandon a bad job or relationship or habit, it could also mean you need to abandon a bad job or habit 

Obviously you are not thrilled to see your own daughter "playing with fire."  Your fears for her future are surfacing now as she begins to age and you desire to keep her safe.  Your subconscious mind has already thought through all of this, and is making you aware of the dangers of her future years, so you can guide her in the right direction. 

Just a parents worries and insecurities about their children. Your brain took an innocent image of your daughter, combined it with something no good parent would want of their children, even regardless of their age.

Dreams don't mean anything.