Just imagine that, elves that are actually intimidating precisely because of their superiority complex, because they view non-elves as dogs created solely to serve them.
Since we're talking about dorfs anyway, imagine a horde of elf horsemen charging down the plains, slaughtering all they come across and demanding precious metals and finely crafted tools in exchange for not committing genocide.>But dorfs live in the mountains, they can easily escape the elf horsemen
But for how long? The elves are patient, they have all the time in the world. And the dwarves need to leave sometime, either to work their fields or to trade with other civilizations who provide them with the food they need. Just make sure nobody enters, nobody leaves and bide your time. And when a dwarf messenger shows up to negotiate, tell them your last demand has been doubled to compensate for all the precious time they wasted. And if they really the dorfs dead, they'll just bully some other race into fighting you for them. And when the last dwarves are on the verge of death in a ditch they take anything they can fit on their horses, burn everything they can't and leave.
The very sound of the elves approaching will have any lord of any race reaching for his coffers, hoping they can be convinced to just move in the opposite direction.