No animal has human beings on its diet. The only animal on Earth known to actually hunt humans is the polar bear, though where it lives, humans aren't exactly plentiful anyway.
The Great White Shark's primary food source are seals and sea lions. There's a reason for that; as sharks, they have to move constantly in the water. They can never stop or they will sink or die. Therefore, they have to eat constantly to provide the energy to keep moving. They need food that is high in fat. Humans are not a good source of energy because compared to most animals, we are very lean and low-fat. Seals and sea lions, on the other hand, are very high-fat and good energy sources.
Most shark attacks on humans are simple cases of mistaken identity. The shark looks at a surf-board from below and thinks its a seal. Usually, after the shark bites once, it loses interest (though one bite from such an animal can be fatal).
Sorry, but many animals have man on their diets. From man eating cats to sled dogs that are not tied up and eat a child or elderly person, predators look at the world in terms of caloric value.
Perhaps what you mean is that animals don't make man a regular part of their diet.