Each time I teach a Puppy Socialization class there's always at least 1 puppy who is terrified to come in the door the first day. The scaredy pup might be growling, hackled or even lunge and air snap. The harried owners look apologetic or get upset with their puppy. They often reprimand their dog.
I have a better idea... let your puppy express him or herself. We don't want to risk turning off "dog language". Growling is an important part of how dogs communicate to us that they feel threatened or scared. We need to know this! Otherwise you might end up with a dog who bites without warning.
Dogs and puppies alike talk to us using an assortment of important body language and sounds. We need to respect those so that we don't end up with a dog that can't communicate. A dog or puppy that won't growl or show teeth is just as likely to bite as a dog that does. The only difference is the one who isn't "talking" will catch people and other dogs completely by surprise.
Puppies come to class and adjust rather quickly. Your best bet would be to let your puppy settle in and just relax for a few minutes. Once they realize that they are safe they might venture around or actually begin to interact with the other puppies. Don't baby your pup but don't get mad at him either.
Marco and friend Maggie demonstrate play even though it looks like they're fighting. Sometimes dogs practice "fighting" or "aggressive" behaviours in play just like small children play house or war.