Cats and Dogs Living Together
I would recommend very slow and controlled introductions. More specifically I would keep contact to very short periods of time initially and I would have the dog leashed or held so that they dog is not able to scare the cat. While the dog may be trying to interact positively with the cats, the cats may not see this as positive behavior. I would make sure that the cats have places to get away and as long as the cats are not being aggressive towards the dog, I would let them get used to the dog in their own time.