Mourners carry a coffin containing a victim of rocket attacks in the Abu Ghraib district on the outskirts of Baghdad on September 29.
Washington has warned that it will not tolerate attacks on U.S. interests in Iraq by Iran-backed militias, as Baghdad voiced concern about a possible American withdrawal.
"We can't tolerate the threats to our people, our men and women serving abroad," David Schenker, assistant secretary of state for near eastern affairs, told reporters at a briefing in Washington on October 1.
Schenker did not confirm or deny a reported U.S. threat to withdraw its troops and close its embassy in Baghdad unless the attacks against them stop.
"We are working, and we look forward to continuing to work, with our Iraqi partners to keep our personnel and our facility safe," he said.
U.S. Secretary of State Mike Pompeo issued an ultimatum last week that all American personnel would leave Iraq unless the Iraqi government puts a stop to a spate of attacks against them.
On September 28, a rocket targeting American troops killed seven civilians near Baghdad -- one of around 40 attacks targeting U.S. interests since early August.
A U.S. withdrawal could lead to further pullouts by members of the U.S.-led coalition fighting entrenched militants, which would be "dangerous, because the Islamic State group threatens not only Iraq but the whole region," Iraqi Foreign Minister Fuad Hussein said.
On September 30, several rockets fell in Iraq's autonomous Kurdish region in the environs of a base used by the Democratic Party of Iranian Kurdistan, a commander for that group said.
Iraqi Kurdistan's counterterrorism service blamed the September 30 attack on the Popular Mobilization Forces (PMF), an Iraqi state paramilitary organization dominated by Iran-backed groups.
"The single biggest problem in Iraq is the Iranian-backed militias that are undermining stability there, and attacking the United States," Schenker said.
With reporting by Reuters and AFP