You could create a Policy that tells the port to drop Multicast traffic, but why would you want to? A lot of essential network services, Routing Protocols (OSPF, RIP, etc), network services like DHCP, IGMP, VRRP, Link-local name resolution, video and audio conferencing rely on Multicast traffic to efficiently get packets around your network. And if configured rightly, Multicast traffic can potentially only account for a fraction of network traffic