Baghdad-based Colonel Steve Warren, who represents the US-led coalition that is attacking the IS group in Iraq and Syria, said about 500 jihadists had carried out an offensive against Iraqi Kurdish peshmerga forces in the northern province of Nineveh on Wednesday.
Coalition aircraft from five nations responded and dropped nearly 100 bombs during the overnight fight, he added.
"Air power alone killed nearly 200 of them, about 187 by last count," Warren told Pentagon reporters in a video call.
"So, a significant blow to this enemy. And then, of course, ground forces. We don't have a good count yet for how much damage the pesh (peshmerga) were able to inflict on this enemy during the course of this fairly long battle. But we know it was significant."
The multi-pronged IS offensive saw jihadist fighters target several areas including a base housing Turkish soldiers that has been at the heart of a bitter dispute between Baghdad and Ankara. Peshmerga forces repelled coordinated attacks in Nawaran, Bashiqa, Tal Aswad, Khazr and Zardik, the Kurdistan Regional Security Council (KRSC) has said.
Warren said much of the fighting took place in Tal Aswad. The KRSC, which is headed by de facto regional president Massud Barzani's son Masrour, previously said that more than 70 IS members were killed in the attacks. Warren said Canadian special operations troops, who are in Iraq to help train Kurdish fighters, helped in the fight on the ground.