No. "Dwarves" and "dwarvish" were deliberately introduced by Tolkien as a way of making Middle-Earth language stand apart from English. He mentions it as a deliberate choice in the foreword.
It's a mark of the popularity of his books that people assume that's the correct spelling in English, because that's the most common form of it they've seen, but "dwarfs" is the correct usage outside Middle-Earth.
It's a mark of the popularity of his books that people assume that's the correct spelling in English, because that's the most common form of it they've seen, but "dwarfs" is the correct usage outside Middle-Earth.