Gufran al-Saidi, a Shia Islamist MP, told reporters after walking out that she had been trying to raise with Mahmoud al-Mashhadani an incident earlier in the week in the parliament's lobby.
In the incident, she said, the speaker's bodyguard had attacked her in a dispute over a mobile phone ringtone.
Saidi said the bodyguard for Mashhadani, who is a Sunni Arab, objected to her aide's ringtone, which played a Shia religious chant that mourns al-Hussein, the grandson of prophet Muhammad who was killed in Iraq.
Sunni Muslims consider any death to be the will of God and so exaggeration in mourning is interpreted as an objection to His will.
Wednesday was only the second normal session of parliament since it was elected in December. Sectarian wrangling has held up formation of a national unity government that Iraqi and US leaders hope will avert a slide towards civil war.