Love them. If they are muscle, you don't really have a choice in size. If your calves were fat, then I could suggest a few core exercises and good foods to help you on your way to replace that fat with muscle. Not everyone has calves like Sienna Miller (or a lack, thereof). Why would you hate your calves? Learn to love them- they are stronger than any twiggy- wannabe's legs.

Aeorobics, treadmills and jumping all help to reduce calf size.