Councils can erect netting to stop balls going onto private property, if the area used is designated as a play area.
You could also try keeping any balls which come over, but don't destroy them, as technically, this's a theft.
Have you tried asking them in a pleasant manner - with a smile on your face - if they could just be careful not to let any balls come over? You could say you have youngsters there, and their actions could be dangerous. If not, contact the police anyway. If enough folk complain, it IS possible to get something done, but by the same token, it's never wise to move into property that's close to a park or where footballs might be kicked!