That’d be a senryū. A proper haiku needs to have a kigo – a word hinting at a season – and kireji, a cut-word.

(And English is on average terser than Japanese: I read somewhere that an approximate equivalent of Japanese 5-7-5 morae is 3-5-3 English syllables, so the syllable count requirement is not absolute. Even Bashō’s famous crow haiku かれ朶に烏のとまりけり秋の暮 is 19 morae rather than 17.)