Tehraninfo-icon - Iranian leadership Thursday reiterated their support for Iraqi government in its battle against terrorists in the west of the country and Kurds in the north but warned the Arab nation of falling in the trap of United Statesinfo-icon, which they called 'untrustworthy'.

Prime Minister Haider al-Abadi won the backing of regional powerhouse, Iraninfo-icon in his efforts to rid country of terrorism and separatist tendencies among Kurdish minority during his visit of Iran which followed his visit to Turkeyinfo-icon.

Supreme leader Ayatollah Sayed Ali Khamenei "gave his support for measures taken by the Iraqi government to defend the unity, sovereignty and territorial integrity of Iraqinfo-icon", leader's office said in a statement after Abadi called on him at his Tehran downtown residence on Thursday.

Ayatollah Khameneiinfo-icon called Iraq a determinant and important country in the Arab worldinfo-icon and supported Abadi's efforts, for developing relations with neighboring countries of the region. Iranian leader however stressed, "Meanwhile, you should be careful about the Americans' mischief and never trust them." 

He went on to say: The USinfo-icon created ISIS themselves; but, now that the terrorists were beaten by the the Iraqi people and government, they pretend to align themselves with this great change; although, they will undoubtedly use any opportunity to strike Iraq again. 

Supporting the comprehensive expansion of the relations between Tehran and Baghdadinfo-icon in various fields, the Supreme Leader addressed al-Abadi, saying: "The region's nations look forward to the success of Iraq: the result of the efforts and braveries of the Iraqi people, you and other Iraqi officials." 

Abadi earlier held talks with President Hassan Rouhani who said Iran "has and always will stand alongside" Iraq "when it comes to fighting terrorism, reinforcing (its) unity and preserving its territorial integrity".

"The fight against terrorism and separatist goals... must be monitored and Tehran wants to contribute to reinforcing the Iraqi central government," Rouhani added, according to the presidency's website.

Buoyed by the success of the campaign against the terror groups and operations against the Kurds, Abadi has been on a regional tour that on Wednesday saw him in Ankara.

The Tehran stop came as Iraqi forces launched a new assault on Kurdish forces in a disputed area of Nineveh province, sparking heavy artillery exchanges, according to Kurdish authorities and correspondents in the region.

Government forces have since last week snatched back control of thousands of square kilometres (miles) of territory long disputed with the Kurds, in a feud which has boiled over since a Kurdish independence referendum held in defiance of Baghdad on September 25.

The vote organised by the leadership of autonomous Iraqi Kurdistan in the country's north angered neighbours Turkey and Iran, both fearful of anything that might stoke separatist sentiment among their own large Kurdish minorities.

Also on Thursday, federal troops and allied paramilitaries launched an offensive up the Euphrates Valley towards the Syrian border in a bid to retake the last ISIS bastion in Iraq.

Tehran has poured significant resources into the warinfo-icon against the terrorism in Iraq, providing weaponsinfo-icon, advice and training to the popular forces known as Hashd al Sha'abi which dominate the paramilitary force.

Iranian involvement has irked Washington but has been defended by the Iraqi prime minister, who gave a firm rebuff to US Secretary of State Rex Tillerson over his comments on the issue.

Abadi has been deeply defensive of his government's close alliance with neighbouring Iran, which like Iraq is a Shiainfo-icon-majority country.

On a visit to Tehran's arch rival Riyadh on Sunday, Tillerson called for Iranian militias in Iraq to "go home" as the fight against IS was coming to a close.

The fighters of the paramilitary force are "Iraqis who have fought terrorism, defended their country and made sacrifices to defeat (ISIS)", Abadi said, according to a statement from his office.