Does one need to make amends for a bad-action done accidentally? Note: Originally I wrote "unintentionally" and not just "accidentally" but I have realized that even the "accidental" action described in the example below involves the person's intentions of their movements and thus even if the person's intention wasn't to break the vase they still broke the vase through their intentional action and I believe they would necessarily suffer for breaking the vase. 

Example: 


A person is walking through a friend's house and accidentally knocks a vase and causes it to fall and break. The friend asks for the person to buy them a new vase, but the person refuses. 


Does the person necessarily suffer for refusing to buy their friend a new vase?
You say "unintentionally" but your friend might see it as "negligence".


I didn't mean to break it!
Yes but you should have looked where you were going! No one else broke it...


I suspect that Buddhism might classify negligence too as volitional, karmically active, and a cause of suffering.

Anyway, I think that arguing about it with the friend probably counts as intentional.

FWIW a civil court might try to apportion blame e.g. based on where the vase was placed. Who knows, maybe it would be appropriate to share the blame.