On Friday, US Defence Secretary Ash Carter suggested Turkey should play a role in the Mosul offensive, but the Iraqi PM Haider al-Abadi balked at the idea, telling the US that there is no need for Turkish forces yet.
Turkey has insisted that its forces cannot remain idle during the fight to drive IS militants from Mosul.
Mr Carter, who is visiting Kurdish officials in Erbil, said the US was planning simultaneous operations against IS in Mosul and in the group's Syrian stronghold Raqaa, AP reports.
He said Washington wanted to begin military operations against IS fighters in Raqaa "as soon as possible".
A US-led coalition is backing the assault on Mosul with warplanes and military advisers.
Some 30,000 Iraqi security force personnel, Kurdish Peshmerga fighters, Sunni Arab tribesmen and Shia militiamen are involved in the offensive.