That's probably a good sign of a good rooster. You want a little "punk" that protects his ladies.
If you want him to back up off of you, and this is a 50/50 chance, take a feed bag in the coop when he runs at you, hold it in the middle and above your head and flap it like bird wings (OK I know this sounds crazy but it has always worked for me and I'm 5+ roosters in). They think it's a bird of prey.. I guess, and they think twice in the future. It might take a few attempts with the bag, but it's always worked for me...