We, as guys, when a female makes it seems she is interested in any amount, will take that idea and run with it. If you like to hang out with them, have fun with them, and tell them so, usually we'll take that to mean more then what you want it to mean. Guys at this age are horny bastards whoes primary concern is getting some, and if you make yourself seem available to them, they will try to take advantage...no matter if you told them your situation. We don't listen, cause we don't care.
However, if they are really your friends and not just wanting more, they will still be your friends even after you tell them you aren't interested. Sometimes we guys will get into a tough spot and confuse lust and love. I doubt any of those guys are in love, probably just in lust.
On a personal note, I have a very good female friend that I care a great deal for, would do almost anything for her. Shes knows it, and feels much the same way about me. But we've never done anything to put the friend ship at risk, because frankly, having her as just a friend and always wondering "what if" is better then not having her at all.