If you inflict “death or serious harm” then no - you cannot be protected under self defence laws (in the NT, not sure about other states).

If you just rough them up a little bit… then yes, there is a self defence provision that will protect you. But only if you get a fair trial, and if your skin is black then you probably won’t get a fair trial - especially in that region of the country. If you call the cops, they’re probably even worse than the security guards.