How can I stop my neighbor's daughter from bullying my child?

Child of my neighbors’ is bullying my child. My child is 12 years old and the girl with whom she has conflict is almost 11 years old. This girl is always asking for all children in our neighborhood to do not play with my child and is calling her names and is asking the other children to call my child in the same way. A few times this girl pushed my child, and she is always trying to provoke a conflict. I am tired to see the tears of my child. My child is afraid to go outside; she is sitting at home and can't play with others children. If my child is going outside she is seating just on our staircase in order to not see that girl, but this girl comes on our staircase and is jumping specifically to provoke a conflict. When my child is playing with other children with the ball, this girl is coming outside at the same time and "and allegedly accidentally” hit my child over the head with a ball. A few children from our neighborhood can prove my words. They saw how this girl pushed my child for nothing, and how she is calling my child. They saw how this girl is provoking my child. I was trying to speak with her parents, but with no results. The parents are teaching their child to behave in this way.