I admire your resolve to shield your dear children from such behaviors as you describe. It seems that all too often it becomes so difficult to monitor the effects that other children will have upon our own children that we many times become less diligent. I can understand your frustration and know that this is a burden for you and ultimately your dear children.
My best advice to you would be to speak with your dear children first. Tell them the house rules (the behaviors that are upsetting and will not be allowed in your home). Explain to them that you will not tolerate this behavior and that should their friends begin in this behavior they will have to leave. Be careful not to be judgmental or unkind when you talk about the other children. In fact it is probably not that necessary to bring the other children's names into the mix. It is best to be very clear about the rules for your household and in so doing you are laying the rules down without regard to another child's ill behavior.
Have a set time of day when friends are allowed to visit. If you feel the need you can tell the moms of the children who usually play at your home and inform them about the time of day that your doors are open and you and your children are ready to entertain. If there is something going on in your household (a sick child, lots of school work to catch up on, etc.) feel totally empowered to explain that you are not receiving guests that particular day when the neighborhood children come to visit.
Many times moms feel at a loss to discipline another person's child. We find ourselves fussing at our own children when it is the neighbor children that are causing the disturbance. It is perfectly natural that you would feel frustrated and concerned. Please do not be overly concerned about explaining your position as I have explained and go forward. You are doing the right action in the face of behavior that is trying and ultimately hurtful.
Let us pray together. Dear Jesus, please show us the correct response to behavior that is hurtful and unholy. Show us the words to use that will affect change in another's heart while at the same time being charitable and kind. Lord, bestow upon us the gift of hospitality and give us the holy wisdom to use our resources wisely when opening our hearts and homes to other. St. Elizabeth of Hungary pray for us.
Sending out a prayer,