If you could capture some video it would help folks see what's going on and be able to better suggest solutions.

Without that, if you could explain some examples in detail, that would help too!

 

When I am introducing animals (which I have done a lot, having fostered dogs for many years), I rend to let them work it out on their own, IF no one is getting hurt or in danger of it, and no one is getting overly harassed. If those things happen, I step in. It is also important not to leave them alone together, and important that each of them have a place to go to get away from the other. For the cat that's usually up high. In this case, if your puppy is smaller than the cat, give him a box he can get into or tie a door in such a way that he can get into the room but the cat cannot. Or, if those things are not feasible for you, then just supervise. But unless the puppy is scared or upset, I would just watch and see what happens.
And, yes, video would help if you can do it. If not, a full description of what you see, perhaps.