Saving oneself from harm

I am a student. Alhamdulillah I have whatever Allah has given me. In my hostel life, people from different rooms and floors comes to me asking for things? I reply with the truth, by saying I have that. Then they ask me to use it. Since I cannot say no, I lend them, but they never return it back to me. As I am a student I have a particular amount of money from my parents to spend for requirements. Now I have decided to tell them I don't have it (here my intention is that I don't have anything to give you, not that I don't have that thing), can I tell them like that? Else what can I do?