RNA - Haider al-Lami told the Arabic-language al-Ahd news website that "the security firms affiliated to the US embassy have killed the protestors".
He underlined the need for revealing the identity of all collaborators in killing the protestors and putting them on trial.
Al-Lami said all political parties and the Iraqi nation and resistance forces should endeavor to eliminate the US-affiliated agents.
Nearly 550 people have been killed in protest-related violence since unprecedented anti-government demonstrations erupted in Baghdad and southern Iraqi cities in October, the Iraqi Human Rights Commission said.
According to Fars News Agency, the Iraqi Health Ministry confirmed the first protester was killed on October 1 but has not issued additional reports on fatalities. The commission, which is government-funded but operates independently, became the only source for death tolls until it faced pressure last year to stop reporting. It resumed its public reporting and published its latest statistics on February 7, showing that 543 people, including 276 in Baghdad, had been killed in protests since October.
Seventeen security forces members were among the dead, the list stated. The remaining were protesters or activists, including 22 who were assassinated.
Up to 30,000 people have been wounded during the rallies, medical sources said.