Islamic State militants detonated a car bomb and then opened fire on Iraqi troops in the western province of Anbar on Thursday, killing 14 soldiers, security sources said.
Iraqi government forces and their Shi'ite militia allies are hoping to recapture Anbar's provincial capital Ramadi, which was seized by the ultra-hardline Sunni insurgents last month.
The Islamic State group swept through northern Iraq last year and has since taken control of a third of the country, which is a major oil producer and OPEC member.
The Islamist group also holds large swathes of Syria.
Twenty-seven soldiers were also wounded in Thursday's attack in Anbar's Nadheem al-Taqseem region.
In the town of Hit, west of Ramadi, artillery fire and rocket attacks targeted the local irrigation department, killing nine people and wounding 13.
The presence of Islamic State militants has fueled a sectarian civil war.
Iraq's army relies on U.S.-led airstrikes and a Shi'ite umbrella fighting group known as Hashd al-Shaabi, or popular mobilization committee, in its bid to a slow the advance of Islamic State fighters.
Kurdish fighters in the north are also seen as a critical force in the battle against the Sunni insurgents.
Meanwhile, the Combined Joint Task Force said an airstrike by U.S.-led coalition forces in Hasaka, a city divided into Syrian government and Kurdish control where Islamic State fighters have been trying to retake the initiative, struck a unit of Islamic State fighters and one of the militant group's vehicles.
Two other strikes in Syria hit near Aleppo and Tel Abyad, according to the statement released by the U.S. military Thursday.
In Iraq, the coalition staged 13 strikes targeting Islamic State fighters near Mosul, Ramadi, Tel Afar, Bayji, Baghdadi and Falluja, the task force said.