I don't have a cat but when the Gwen Bailey book, "The Perfect Puppy", discussed it, she said to let the cat have higher ground (e.g. sofa) and pup on the floor, and hold onto the puppy, so that the pup knows that it can't chase the cat, even if cat decides to leg it.
The only contact Paddy (15 weeks old this week) has had with a cat didn't go well. I did as above, all fine - at a friend's house. Just as we were leaving several hours later, Paddy just bumbled into the cat and got swiped in the eye. The screaming was unbelievable, and when I looked at his eye, it looked like there was a lump of raw liver hanging out of it. Rushed to vet on emergency appointment: nothing wrong, dogs and cats have a third eyelid, and this had popped up to protect his eye, and us poking/squeezing the eye had made it pop up again. For me though, this "near miss" reinforces the common sense of what Gwen Bailey says - hold the puppy back!