Security and hospital officials said the protester died when he was struck with a rubber bullet fired by security forces on Rasheed Street near the strategic Ahrar Bridge.
The officials spoke on condition of anonymity in line with regulations.
Protesters are occupying part of three key bridges — Jumhuriya, Ahrar and Sinak — in a standoff with security forces.
At least 17 protesters have died in renewed clashes, which kicked off last Thursday. The historic Rasheed Street, known for its crumbling architecture, has been a flashpoint in the recent violent escalations.
Security forces have used live ammunition, tear gas and rubber bullets to repel protesters from scaling a barricade.
Over 350 people have died and thousands more wounded since Oct. 1, when thousands of Iraqis took to the streets to decry rampant government corruption, poor services and scarcity of jobs. The leaderless uprising seeks to dismantle the post-2003 political system.