Attack is the political position many anarchists come from.
What attack looks like looks different in different situations. I don't want to go in depth into this related to this question, but I do want to say that attack is not just smashy. Smashy is fun and beautiful, but smashy alone does not make attack, and Attack is not limited to the obvious examples of breaking shit and fighting cops.
As to your (anonymous asker) question, I would agree with dot that the particulars are important in that sometimes there is a police riot: the people are demonstrating and then the cops attack and the people break shit/fight back. But there are also offensive actions. Not going in to specifics, I can think of several things I have gone to where I knew the intention would be to escalate tension and use that as a moment.
The moments I am talking about is what the insurrectos would refer to as ruptures. Places where a tear in the fabric of social cohesion occur. These tears aren't dependent on smashy, in fact, they happen all the time without such. Smashy is a spectacular example of the rupture, and it is an easy way to demonstrate how anti- you are, and it is attacking things we hate (even if those things are just widows), and it is cathartic. Also, given the situation you describe, where the cops attack first, why not destroy as much as possible?
Personally, I am more interested in barricades against the cops and such, but I am glad that some of my friends are less reactionary and look towards opening more space from the confines of window displays.