If stuff like this happens, the best approach is to act as if nothing had happened. Pretend that you didn't know and that things are still cool. Don't act all awkward around anyone. This will show your level of maturity.
And since your crush thinks that you are obsessed with him, show that you aren't. This time, prove to him that you have other things on your mind by ignoring him for a bit. Of course don't do it excessively but enough times to prove your point. Telling someone to tell him that you aren't kind of defeats the purpose of you not being obsessed. This shows that you care about what he thinks. It isn't a sign of obsessions necessarily, but it definitely isn't a sign of indifference. You need to show that you can be indifferent to him too, that you are not someone who he can easily get. That's how you let your crush know that you aren't obsessed with him. Actions speak louder than words.