To dream of a major demonstration involving placards and police is your unconscious making it very clear that you may be involved in a situation that will not serve your highest good.
To dream of a small demonstration of a kitchen implement or sporting skill indicates that you will find yourself becoming interested in an unusual hobby that could give you hours of joy.
[1]Were you participating or watching? What were your feelings during the dream? Who demonstrated for what? And the most important question that you have to ask yourself is: What would I be demanding or wishing for.7 What purpose motivates me.7
[2]An outward display, whether formal or informal
[3]