Negative Physical Reactions

I am having trouble with my four year old son, but first just a little bit about him. He is a very strong minded chap, very active, and loves to be involved with everything. He especially enjoys being sociable with others, and is always asking other to play with him or getting involved with games already happening. Hence, the problem begins. He will often try to force his ideas in a physical way. For example, he is playing with blocks building a tower, or riding a scooter and decided that he wants someone else to do it too, normally his little sister, or another younger boy who lives in our household. Instead of asking them if they want to and giving them a chance, he will push and shove to get them to comply. Of course this all results in loud vocal displeasure, and more often than not the younger child getting hurt in some way. Adult intervention at this point often means that he become physical with them too. When talking to him the other night he said about his little sister, "she wanted to play with me." Not thinking for one minute that her screaming meant the exact opposite.