If the story is too large to fit into a sprint then it should probably be an epic. You would then break this epic down into smaller stories and then break these down into tasks. In that way you can spread the completion of the epic over several iterations while always being able to complete the stories that make it up (and therefore hit your sprint goal).
If you can't split the story into parts that are small enough to complete in an iteration then there's a problem with how the story has been written or with the techniques you are using to decompose it. It doesn't matter (in my view) whether the tasks will only take a few hours but if you think these are too small then you could try and bundle a few related tasks together so that you don't feel like you're measuring something that's too small to meaningfully measure.