BAGHDAD:The U.S. State Department said Tuesday it was outraged by a rocket attack a day earlier that killed Iraqi civilians and called on the government to take action amid an impending diplomatic crisis between Baghdad and Washington.

The attack and subsequent condemnation come after the U.S. threatened to close its embassy in Baghdad unless Prime Minister Mustafa al-Kadhimi's administration reins in Iran-backed armed groups responsible for frequent rocket fire and roadside bomb attacks targeting the American presence in the country.

“We are outraged by yesterday’s rocket attack in Baghdad that killed civilians, including a mother and her children,” State Department spokeswoman Morgan Ortagus said in a statement.

In response to the embassy closure threats, the prime minister's spokesman said in his weekly news conference Tuesday that the closure of any diplomatic mission would have detrimental consequences for regional security.

“The withdrawal or closure of any diplomatic mission of any country will have disastrous repercussions for the entire region,” said Ahmed Mulla Talal.

He said the al-Kadhimi administration rejected any attempts to turn Iraq into an arena of conflict between the U.S. and Iran.

The attacks have not let up, despite the U.S. threats.

On Tuesday a roadside bomb targeted a convoy carrying materials for the U.S.-led coalition in Babylon province, south of Baghdad, according to a military statement. There were no casualties.

A Katyusha rocket attack struck a residential home killing six civilians, all women and children, the night before. Initially, Iraq's military reported five killed, but one child died of severe wounds overnight.

Iraqi security officials believe the rocket was intended for nearby Baghdad airport, a frequent target of such attacks, where U.S. troops maintain a presence.

The attack was not claimed by any group, but U.S. officials believe Shiite militias aligned with Iran are responsible for that attack and others that have targeted Americans on a near-daily basis in recent weeks.

Often, they have targeted the U.S. Embassy in Baghdad, within the heavily fortified Green Zone, and U.S. troops present on Iraqi bases as well as the Baghdad airport.

Roadside bombs have also frequently targeted convoys carrying equipment destined for U.S.-led coalition forces.

“We have made the point before that the actions of lawless Iran-backed militias remains the single biggest deterrent to stability in Iraq,” Ortagus said.

“These militias pose an unacceptable danger to everyone in Iraq, from diplomatic officials and facilities to Iraqi activists and families.”