Is it obligatory to pay blood money (diyya) for someone who accidentally killed a cat?

There is no sin upon one who kills cats or other animals by mistake or unintentionally, for Allah Almighty says: (And there is no blame upon you for that in which you have erred). As for intentionally killing non-harmful animals, it is not permissible, and one must seek forgiveness for it. However, there is no compensation or charity required from one who kills them by mistake. The Hadith about the woman punished for a cat is in the context of intentional harm and abuse, not error.