When I was growing up my mum used to leave the animals to get on with it be it a new pup or kitten, they soon learnt to leave the older animals alone and when it was ok to play. At 14 weeks old the pup doesn't know that the cats don't want to play all the time and probably sees them as playmates, I'm sure the cats will let the pup know when they want to be alone, after a while I'm sure the pup will ignore the cats. We've never had any major problems with cats and dogs apart from a couple of scratched noses when they've refused to leave the cats alone and have cornered them, but after that all has calmed down.