Deputies suspended their session on Tuesday for an hour in protest against the incident involving Fatah al-Shaikh, a follower of Shia cleric Muqtada al-Sadr and member of the dominant United Iraqi Alliance (UIA) bloc, Aljazeera reported.
They then voted unanimously on a motion demanding an official apology from the US embassy and Washington, and the punishment of the US soldier involved.
"When I told the translator with the soldier that I was a member of the National Assembly, he answered: To hell with you and the National Assembly," al-Shaikh told his colleagues.
In an interview with Aljazeera, al-Shaikh said the fracas started when he was on his way to parliament and had lined up in his car with other deputies to enter the Green Zone, the seat of the transitional government and home to the US embassy, foreign advisers and contractors.
"When I told the translator with the soldier that I was a member of the National Assembly, he answered: To hell with you and the National Assembly"
Iraqi member of parliament
"While I was on my way this morning to the National Assembly, US forces surprised me by kicking my car several times in the presence of a group of my colleagues from the assembly while my car was among 15 other cars waiting to be admitted into the Green Zone," he said.
The Iraqi lawmaker said one particular US soldier targeted his car more, seemingly angered by the posters of Shia leader Muqtada al-Sadr that his vehicle displayed.
"One US soldier appeared to be designated to my car in particular, as it carried the picture of Shia leader Muqtada al-Sadr.
"As though he was antagonised by the picture, the US soldier began to utter some words in English which I did not understand. When I handed out my MP badge and showed it to him, he threw it at my face, opened the car door and pulled me out."
Speaker al-Hasani said he might
suspend assembly sessions
Al-Shaikh said he was roughed up by the US soldier despite his protestations.
"The soldier twisted my hands to the back in an effort to handcuff me.
"The soldier began to beat me and squeezed me by putting his arm firmly around my neck. Then they pulled me off to a nearby room 10m away in their headquarters."
Al-Shaikh said the US soldier continued to beat him even after he told them that he was an elected MP.
The US military said it was investigating the incident and refused to comment.
Insult to injury
At least three other deputies said they witnessed the mistreatment of al-Shaikh.
"I saw the whole thing and adding insult to injury was when Iraqi soldiers drew their rifles at brother Fatah as he was being mistreated by the Americans," Ali Yushaa, an independent Shia MP, said.
Deputies took turns to speak for almost two hours about the many indignities that they and the Iraqi population suffer when coming in contact with US troops.
"According to the Geneva conventions, an occupying force must respect the occupied nation. This offending soldier must be thrown out of our country"
Abd al-Khaliq Zanganah,
Kurdish member of parliament
"According to the Geneva conventions, an occupying force must respect the occupied nation," Abd al-Khaliq Zanganah, a Kurdish MP said. "This offending soldier must be thrown out of our country."
A Sunni MP, Mudhar Shawkat, handed in the green VIP badge issued by the US military authorising him and other deputies to enter the Green Zone and said he would only attend parliament if sessions were moved to another location.
"They should be put on notice and given two months - no more - to leave the Green Zone," he said, before walking out.
Another unidentified MP shouted: "Yes, the end of occupation begins here. The Green Zone must be liberated from occupation."
Speaker Hajim al-Hasani said he would suspend sessions altogether unless they moved within a week to a building on the fringes of the Green Zone that has its own entrance and would be guarded by Iraqi soldiers.
Aljazeera quoted al-Hasani as describing the incident as an assault but adding that a US investigation was under way.
"Enough is enough", he said before adjourning parliament until Sunday.
The sprawling Green Zone used to house Saddam Hussein's Republican Palace, whose annex is being used now as the US embassy.