"We understand that more than 25,000 Iraqis exercised their constitutional rights to freedom of assembly and freedom of expression on February 25.
Demonstrations took place in over 40 cities," said Tommy Vietor, spokesman, National Security Council (NSC).
Overall the demonstrations were peaceful and for the most part Iraqi Security Forces (ISF) behaved professionally and with restraint, he said.
"We deeply regret that several protests turned violent," he said.
The US has received preliminary reports indicating that the violence resulted in the death of at least 12 civilians and the injury of more than 100 civilians and 100 members of the Iraqi Security Forces.
"We were also deeply troubled by reports that Iraqi Security Forces detained and beat Iraqi journalists and civil society leaders during Friday’s demonstrations," Vietor said.
"We note that the government has now issued a statement pledging that the Iraqi Security Forces will not subject journalists to such treatment again.
We underscore the need to respect the freedom of the press, throughout Iraq including in the Kurdistan region," he said.
The United States welcomes the decision of the government of Iraq to investigate these incidents and its commitment to hold accountable those responsible for the improper use of force and violence, Vietor said.
"We also welcome the decision by the Kurdistan Regional Government to investigate the use of violence by Kurdish security forces in responding to demonstrations held in Sulimaniyah beginning on February 17 and reiterate the need for accountability," he said.
"We encourage the Iraqi Government and the KRG to respond to the legitimate grievances and concerns expressed by the demonstrators," Vietor added.