Hi Rennie, welcome to Pet Talk. I am not a trainer, and have no special knowledge or experience, but...(you knew that was coming didn't you?), a lot of puppies do pull and bite on the leash while walking. I do not think it is an attempt to play, I believe it is a dominance thing. You need to take the control away from him. When Ginger would do it, I would tell her no, then tell her to sit. When we were still in training I would always take treats with us on our walks, because we would usually need them for attention and correction. Anyway, tell her to sit then reward good behavior (eventually you will use just praise, and then praise every two times, etc.). I believe that while on a walk, "sit" is one of the best control words you can use. Once he learns that you are in charge, and you decide how fast, where, and when you walk, he will no longer be trying to get the leash.
He is adorable.