If it's ceramic (which it probably is? google tells me maybe), you can definitely sand it down. Just use sandpaper, or a dremel tool if you have one and want to be fancy. If you have neither sandpaper or a dremel, you could try rubbing it on a patch of concrete (though this obviously depends on the shape of the break).
However, important safety warning, do all your sanding outside. Clay dust usually contains silica, and silica is like tiny shards of glass, i.e. it can cause permanent lung damage. Which is almost certainly not an issue at all for you, because the quantity/exposure is so slight, but might as well be smart. So don't inhale the dust, sand outside, and then wipe with a damp cloth to get as much dust as possible off.
Also, because it fell, there may be hairline cracks, which could expand in a hot oven and surprise you with more damage. Or not -- you'll find out by using it! Which you should be fine to do. Unglazed ceramic does not become less safe just because it has some chips and dings, really, and it should be fine once you've sanded down any sharp edges.
