Iraqi officials made the promise to pursue justice after the last Camp Pendleton Marine facing charges in the case reached a plea deal with prosecutors.
Staff Sgt. Frank Wueterich pleaded guilty to dereliction of duty, was demoted to private and will pay a fine. He will not serve jail time.
Wueterich ordered his squad to storm several Iraqi homes after a roadside bomb killed a fellow Marine in 2005. Women and children died as a result. He apologized for the loss of life, but maintained he acted honorably.
The Associated Press says Iraqi official Ali Al-Moussawi promised to seek justice in the case, after calling it a big crime against civilians.