It may be because of dominance issues.. or maybe it's just being a bratty puppy. Either way, NILIF should be used. NILIF (nothing in life is free) will allow the puppy to realize that everything good comes from the alpha.. you. All meals, all tummy rubs, all pats on the head, all treats, etc have to be earned (sit, down, etc).

On top of NILIF, let the puppy know that it is not an acceptable behavior. A quick, firm "No!" and placing the puppy back on the floor should solve the problem.

If the puppy continues to climb back on your lap and bark/growl at you, put it in it's crate, another room, anywhere that'll seperate the puppy from its "pack".

Good luck!