I'm not willing to accept liability for my renter's dog
Why won't you accept liability for your renter's dog?
The dog is aggressive and bites people. I don't want to be responsible for those injuries.
I understand your concern about the dog.   Make sure that you are not violating the rules and that you are legally able to enforce the guideline that you set in order to avoid any legal trouble.
The renter is responsible for the damages the dog does, it's not going to be me.
If you've allowed the renter to have a dog at your property, you are going to have to be liable if it bites someone. Talk to your renter and ask them to give up the dog or move out. You could ask you lawyer for what would be the best course of action.