Allowing your dog to chase anything is an irresponsible thing to do. Behavioral problems like chasing are more than just annoying. Solving this problem is possible though, but it will take some effort to correct.
It is not as simple as just yelling at or hitting your dog after it has chased something. You might think that doing this would make it less likely to do it next time, but it rarely does. It's instincts will kick in again next time around and the pain it suffered last time will be soon forgotten. Taking a proactive approach, rather than a reactive one, is much better.