Radical Iraqi Shia cleric Moqtada Sadr has called for a truce to be restored after a day of heavy fighting between his militias and US troops in Najaf.
Sadr has repeatedly called for foreign troops to leave Iraq
At least seven Iraqis and a US soldier died in Thursday's clashes and a US helicopter was shot down, injuring two.
But Mr Sadr's spokesman said the cleric wanted to renew the truce in the holy city agreed with US troops in June.
That deal came after Mr Sadr's Mehdi Army militia of mainly Shia Muslims began fighting US forces in April.
"Sadr announced that we are committed to the truce and that [US] forces must honour the truce," Mr Sadr's spokesman Ahmed al-Shaibany told to the Associated Press news agency in Najaf.
Spokesmen for the cleric in Baghdad also said Mr Sadr wanted to continue the ceasefire.
Hundreds died in the Shia uprising but Najaf has been relatively calm since the ceasefire came into force, and there was some concern that the latest fighting could unravel the truce, the BBC's Alastair Leithead in Baghdad reports.
He says tension has been building in Najaf in recent days and fighting finally erupted on Thursday morning.
The helicopter's crew was recovered alive, the US military said
The governor of Najaf requested back-up from US marines after the main police station was attacked, the US military said, but a spokesman for Mr Sadr said US forces and Iraqi police had attacked first.
Iraqi hospital sources said at least seven Iraqis had been killed and dozens injured.
One US soldier was killed and five others wounded in an ambush on a convoy outside the city, the US military said.
A correspondent for AFP news agency said the streets of Najaf were deserted after the clashes in the city centre and at a cemetery.
There were more clashes across Iraq on Thursday.
In Basra, at least two Mehdi Army members were killed in a 15-minute gunfight with UK troops.
A local Sadr spokesman, Sheikh Saad al-Basri, said the militia would fight a jihad against "foreign troops" and any Iraqi security forces who backed them after four men were arrested by the British.
In Baghdad, at least six people were killed and 20 others hurt when an attacker drove a minibus up to the police station and detonated explosives.
Separately, gunmen shot dead two police officers in the Mahawil area.