It all happens so fast that Victor isn't allowed to protest and when she does she does it loudly. She doesn't understand what purpose an attack serves at this point, other than to make the spell fall apart faster by poking at it; they were holding up fine without physically antagonizing the creature they have in the cage.

Why did you do that? thinks a very upset Victor. You didn't need to make an attack!

It's not because she's a pacifist, it's because it literally doesn't make sense to her, when they were on a roll, when they could have kept him longer.