
This is a very common reaction from an older animal (especially a male) at the introduction of a puppy. Many dogs are positively scared of puppies, and of course are likely to feel jealous at the presence of the 'usurper'.
Basically you need to watch the two of them together carefully for at least a week - never leave them together unattended. Even if the adult accepts the puppy straight away the pup can easily be hurt during play - if the adult isn't certain about the pup it could do it serious damage.
Make more of a fuss of your older dog than the pup - he needs to feel that he's not being neglected in favour of the new one. Every time you feed the pup give him a couple of biscuits (from his normal day's ration) in his bowl too - but make sure the pup is well away from his bowl. Don't let either of them steal each other's food, ever.