The one thing you want to avoid is letting him think growling will get him what he wants (to be left alone). Ignoring it will usually work. However, it is unwise to provoke a reaction you might not be able to control. With my guy, I will be diplomatic if he is comfortable. I might sit beside him and complement him, stroke him, then pick him up. Usually that defuses his annoyance. If I do start to pick him up and he growls, I just go ahead with what I am doing. The snarking is usually only momentary. But be smart and keep your face away from his, just in case!
F