* Iran leader says Iraq conflict is not sectarian
* Washington seeks to reassert control of Iraq - Khamenei
* Khamenei makes no mention of cooperation with U.S. (Adds Rafsanjani, head of Basij, paragraphs 3, 17-20)
By Mehrdad Balali
DUBAI, June 22 (Reuters) - Iran's top leader rejected possible intervention in Iraq by the United States or other outside powers, accusing Washington on Sunday of trying to manipulate Iraqi sectarian differences to retake control of the country it once occupied.
In remarks published by the official IRNA news agency, Supreme Leader Ayatollah Ali Khamenei added that Iraqis themselves could end violence in their country, where Iran has steadily built up its own influence over the past decade.
Another senior figure, former President Akbar Hashemi Rafsanjani, said Tehran did not want to meddle in other nations but also hoped to mediate to "extinguish the fire" in Iraq.
Khamenei, who has the last word in all matters in Shi'te Muslim Iran, said: "American authorities are trying to portray this as a sectarian war, but what is happening in Iraq is not a war between Shi'ite and Sunnis."
"It is indeed the same old hegemonic order using leftovers of the Saddam (Hussein) regime as its key pieces, and the Takfiri dogmatic elements as foot soldiers," he told judiciary officials, using a term referring to Sunni Islamist militants.
Masked jihadists of the militant Islamic State of Iraq and the Levant (ISIL) have captured swathes of northern Iraq this month, aiming to create an Islamic Caliphate which ignores boundaries set by colonial powers a century ago.
The advance has been driven by an amalgam of Sunni tribal and Islamist militias, and former officers of Saddam Hussein's Baath Party, united in hatred of the Shi'ite-led government, which they accuse of marginalising their sect. But ISIL has spearheaded the revolt and assaults on cities and towns.
Iranian President Hassan Rouhani has said his countrymen will not hesitate to defend Shi'ite shrines in Iraq if need be, but he has also said, like Khamenei, that Iraqis are capable of doing that job themselves.
Thousands of Shi'ite Iraqis have responded to calls to take up arms and defend the country against the insurgency.
Khamenei said he was strongly opposed to intervention by the United States or other countries in Iraq, adding Washington wanted to re-establish control over the oil-exporting country.
"The U.S. is seeking an Iraq under its hegemony and ruled by its stooges," Khamenei was quoted as saying.
Khamenei made no mention of possible cooperation with the United States on Iraq, an idea that Rouhani, in answer to a question at a June 14 news conference, said Tehran might consider if Washington tackled "terrorist groups" in the region.
U.S. President Barack Obama on June 19 offered up to 300 Americans to help coordinate the fight against ISIL, but he also urged Prime Minister Nuri al-Maliki, an ally of Iran, to do more to heal the country's sectarian rift.
Obama held off granting a request for air strikes from Maliki's Shi'ite-led government, but earlier this month he ordered an aircraft carrier into the Gulf, readying it in case Washington decides to pursue a military option.
Khamenei said the conflict in Iraq was not sectarian, but was instead between those who wanted Iraq in the U.S. camp and those who sought Iraq's independence, IRNA reported.
The armed campaign "aimed at disrupting Iraq's stability and tranquillity, and threatening its territorial sovereignty ... the row is mainly between those seeking an independent Iraq and those who want Iraq join the U.S. camp."
Rafsanjani, a close ally of Rouhani who chairs Iran's Expediency Council, which advises the supreme leader, said: "We don't want to meddle in other countries' internal affairs, but hope to be good mediators in trying to extinguish the fire."
But he said Iraq's plight was complicated because its sectarian conflicts "have taken on the hue of blood."
Mohammad Reza Naghdi, the hardline commander of a volunteer Islamic militia known as Basij, echoed Khamenei's criticism of Washington.
"America is in need of Iraqi oil and its whole effort is bent on recruiting anti-Islamic and fanatical groups to strike a blow against the Islamic nation," he told IRNA on Sunday. America was harming Iraq by hiring people from Iraq's Baath Party and mobilizing them under the banner of ISIL.
Iran's regional rival Saudi Arabia has repeatedly voiced opposition to any foreign intervention in Iraq, in an apparent message to Tehran.
Saudi Arabia and most other Gulf Arab countries were aghast when the U.S. occupation after Saddam's fall in 2003 brought about elections that empowered Iraq's Shi'ite majority. (Reporting by Mehrdad Balali, Writing by William Maclean; Editing by Jon Boyle)