google define: 1. ready or likely to attack or confront; characterised by or resulting from aggression. 2. behaving or done in a determined and forceful way.
Going off the above definitions I don't think it is, but depends on context?
e.g. Jim from accounting is very aggressive, he doesn't take any crap from anyone. (I see how assertive would fit better here but can 'aggressive' be used to convey same meaning?)
Is 'assertive' a nicer way of describing the same traits or does it have an entirely different meaning?
This article seems to think that it is very negative but I'm not convinced. https://englishhelponline.me/2011/09/09/the-difference-between-words-aggressive-and-assertive/