I agree with the above. Don't muzzle him; there's simply no need. He's being social but in many owners' eyes, this is too full on. If you can select who he plays with, fine. If you would personally like to work on the behaviour, I would keep him on a training lead (2 metres, or perhaps a 5mt one) and do the following:

1) Allow him to meet as normal
2) As soon as gets a little grabby, just simply pull him away and say one, clear, distinct 'no'.
3) As soon as he's away and given you some eye contact (even if only for a second) let him interact again.
4) If he grabs again, repeat (perhaps keep him slightly longer to make it clear that doing this means the end of play).

Obviously, this is difficult if the other dog doesn't leave your dog alone! But if it can be done, I've found this to be good way. Simply, it takes away the most desirable thing: the interaction with the other dog.