Don't talk to them =D
No, just kidding!
Just be aware that many introverts communicate a little differently than you (assuming you're an extrovert). Just because they don't chat all the time, engage in every conversation, directly approach new people etc does not mean they do not like hanging out or talking about different interests. They just listen more than tell. They enjoy the company of others, but probably prefer being with few friends rather than an entire village.
People often prejudge introverts as anti-social, rude, and exhibiting low self-esteem. All stereotypes like most labels!
Just remember that although introverts do not constantly express themselves openly, they're still like-minded individuals and they might even be more empathetic than most people you know. They just don't always go out of their way to express all their thoughts and emotions publicly :)