Check out this great video on body language of dogs.
Puppy biting, or mouthing, is a a play behavior young dogs exhibit that can grow into a behavioral problem if not addressed at a young age.
Using verbal reprimands and positive reinforcement, you can stop this behavior and prevent future problems.
How to keep your dogs attention on YOU and not on the other dogs? Socialize your dog to you! Fetch is a great way to play with your dog and the goal would be your puppy wanting to play with you, his or her family, and ignore the other dogs!