The dog was out of its owner's control. It gave chase, and the chase resulted in injury and property damage.

I'm well aware that there were no bites. I wouldn't hesitate to use the term "attack" with the police. The tone of the owner's response and how seriously the police regard this incident will probably change quite a bit.

Who knows...maybe the dog would have bit if it hadn't been impacted by the bicycle it was chasing? I certainly don't...and neither do the police. And the owner can't reasonably swear to that either. Whatever the case may be, the owner is responsible for the damages. The term "attack" may prompt more assertive action.