Non-combatant Pub goers should NEVER be told to shut up. A pub is by definition a Public space and if you're worried about them not listening go to a Folk club instead.
If musicians at the session talk when you play and don't join in you're not playing the right kind of stuff, or they don't know it. But don't let it worry you, persevere if you think the tunes are good and eventually some one will join in and the rest will follow (might take a few tries though, but playing on your own in a session strengthens the spirit).
Another approach might be to take up the Highland Pipes and then you don't have to give a stuff if anyone talks or not.

All the best pp.