Simple. You don't respond to their messages. When you run into them and they ask you why, you just respond that you've been extremely busy and other white lies. That's how it works. Eventually they either get the message or they lose interest.
Only when they persist, you might have to turn out the heavy artillery of outright rejection or telling them off in a polite manner.
Then again, they can be used to improve your game (you're not anxious because you don't want anything from them) or gain access to their hot friends. Or course, this sort of subterfuge is something that has to click with your honour.
Good luck.