Quote from : The Hobbit: The Battle of the Five Armies Movie

Bard: [to Thranduil after failing to negotiate with Thorin] He will give us nothing.
Thranduil: Such a pity. Still, you tried.
Bard: I do not understand. Why would he risk open war upon his kingdom?
Thranduil: [unsheathes his sword] It is fruitless to reason with a dwarf. They only understand one thing.