Are you stupid? You can't send a DDoS back to someone with a firewall and even if you tell the police they won't do anything. DDoS is using multiple computers to send packets so that means multiple IP's. What the hell do you think the police are going to do to someone DDoS'ing a Minecraft server? That's right... Nothing.
Your best bet is to just wait it out or contact your hosting company if you have one about it or if you have the money buy DDoS protection.
