Assuming the cats are not yours, harass them. They are on your property.
I had a neighbor's cat regularly peeing and pooping in the flower bed beside our front porch and front door. Whenever I watered things it stunk like ammonia because of all the cat pee. I spoke with my neighbors and they said they couldn't control where their car went when it was outside.
So, I got some jaw breaker-sized rocks and started hurling them at the cat when I saw it in our yard. After a couple of weeks, and a couple of direct hits, the cat avoids our entire front yard. Now the cat has taken to another house, across the street. Not good, that neighbor will be even less tolerant then I was.
It is irresponsible of cat owners to let cats wander like this. It's also irresponsible for dog owners to let their dogs bark for hours.
Scott