My puppy is also rough with my cats.
He doesn't mean to harm them but he tries to nibble on their ears and he smacks them with his paw and sometimes falls on them.
What I started doing is I took my most laid back cat and I have her lay down while I softly speak to her and pet her and I let my puppy come sniff her. When he starts to get a little rough I tell him no and push him away a little. He is starting to get a lot better. He sometimes still chases them when they run but I tell him "no" and it makes him pause for at least a second.
Just last night my Queen B cat decided she likes him and she licked his face and rubbed up against him, so we are making progress!
Sinister "The Prince of Darkness" 4 yr old black male GSD 3.11.09
Draco "Dakota's Unbreakable Vow" 5.5 mth old male Dalmatian 6.30.13
Cats: Chaos, Mayhem, Monster, Wicked