Reuters - Iran is calling on the Iraqi people to show restraint, an Iranian government spokesman said on Monday, after six days of unrest in Iraq in which more than 100 people have been killed.

�Iran will always stand by the Iraqi nation and the Iraqi government. We are calling on them to preserve unity and to show restraint,� government spokesman Ali Rabiei told a news conference.

The unrest is the biggest security and political challenge for Prime Minister Adel Abdul Mahdi�s government since it took power a year ago.

Clashes between police and anti-government protesters have revived fears of a new spiral of violence that could suck in influential militia groups and be exploited by Islamic State (IS).

The Popular Mobilisation Forces (PMF) - Iraq�s umbrella grouping of mostly Shia Muslim paramilitaries backed by Iran - played an important role defeating IS and formally became part of the armed forces last year, reporting to the prime minister.

Some Iranian officials have accused the United States and Israel of stoking the unrest in Iraq. A cleric said on Friday the unrest was planned by Tehran�s longtime foes to disrupt a major annual Shia Muslim pilgrimage planned to be held there this month.

Rabiei also said Iran would continue efforts to ease tensions in the Persian Gulf by improving ties with its Persian Gulf Arab neighbours.

Tensions between Iran and its regional allies have risen after attacks on Saudi Arabia�s oil facilities on Sept. 14 that Washington and Riyadh blamed on Tehran, raising fears that a direct confrontation could lead to a new war in the Middle East.

Tehran has denied any involvement in the assault, which Yemen�s Iran-aligned Houthi movement said it carried out. (Writing by Parisa Hafezi; Editing by Toby Chopra and Timothy Heritage)