UFC star Rose Namajunas says she was downright OFFENDED by Conor McGregor's pathetic attempt to apologize for that whole bus attack thing ... because he only reached out over Instagram.
Remember, Rose was on the bus at Barclays Center when Conor and his goons went berserk -- and Dana White told us she nearly broke her hand in the chaos.
Now, Rose is explaining what happened in the aftermath -- saying, "I did get an Instagram message from him, but I don't really know if that was really him.