U.S. Secretary of State Mike Pompeo has said Washington was "outraged" by violence against protesters in the Iraqi city of Najaf and he urged Baghdad to "immediately address legitimate grievances."
Pompeo's statement on February 6 comes day after at least eight Iraqi protesters were killed when supporters of influential Shi'ite cleric Muqtada al-Sadr stormed an anti-government protest camp in the southern city, attempting to clear the camp of demonstrators.
The populist Sadr initially backed the demonstrations but split with them over the past few days, endorsing Muhammad Tawfiq Allawi, who has been designated the country's prime minister.
Sadr, who previously said he opposed all foreign interference in Iraq, has aligned himself more closely with parties backed by Tehran in recent months. Iran has great influence among much of Iraq's Shi'ite population and supports powerful militia groups in the country.
Baghdad has attempted to balance its relations with Tehran and Washington, which also provides crucial economic and military aid.
The clashes in Najaf are just the latest in a series of deadly confrontations in Iraq.
For months, anti-government protesters have demanded an end to foreign influence in the country and for what they described as "elitists" to resign from power. The actions led to a brutal crackdown by security forces, with hundreds of protesters being killed.
"Since October of last year, peaceful demonstrators have taken to the streets to urge government reform. They have been met with threats, brutal violence, and live-fire attacks," Pompeo said in his statement.
"It is unconscionable that the perpetrators continue to act with impunity. Political figures who incite this violence and government leaders who fail to take steps to protect rights to freedom of expression and peaceful assembly must be held to account."
Pompeo in his statement put the casualty tolls at "more than 600 protesters" killed and "thousands injured."
"We urge the government of Iraq to take immediate steps to hold accountable the militias, thugs, and vigilante groups in Najaf and other cities for their attacks against Iraqis exercising their right to peaceful protest," he said.
"To the courageous Iraqi people seeking reform and a government free of corruption and Iranian meddling, we offer America's continued friendship and support. We reaffirm the United States' enduring commitment to the Iraqi people and a strong, sovereign, and prosperous Iraq."
The message comes amid strained relations between Baghdad and Washington following the January 3 killing of a senior Iranian commander, Major General Qasem Soleimani, in a U.S. air strike in Baghdad, sparking calls for the pullout of U.S. forces from Iraq.