HR & Labour Law advisor
I am NOT really sure what your Manager means by being 'aggressive'.
It's always an advantage--like B.Saikumar mentioned--to be polite & Soft spoken in ANY & EVERY field.
But this is NOT to be mistaken as 'docile' & 'weak-kneed'. One can be polite & yet FIRM in speech & action.
Suggest speak to your Manager one-to-one on what he expects from you & then you can calibrate your responses.
And, like B.Saikumar mentioned begin to focus on doing your MBA. This will be a MUST at some point of time in your HR career. So handle it when you aren't under pressure to do it.
All the Best.