Al-Maliki had thanked Iran for its "positive and constructive" work in "providing security and fighting terrorism in Iraq" on a visit to Tehran, according to the state-run Islamic Republic News Agency.
 
Iranian leaders told the visiting al-Maliki that they wanted Iraq's friendship and would do all they could to boost Iraqi security.
 
Warm relations
 
Al-Maliki's talks appeared to confirm the increasingly warm relations that have emerged between majority Shia Iraq and overwhelmingly Shia Iran following the fall of Saddam Hussein's Sunni-dominated regime.
 
Al-Maliki reported thanked Iran for its "positive
and constructive" work in Iraq [AFP]
In a highly symbolic move, al-Maliki met the families of seven Iranian officials arrested in Iraq by US forces on accusations of being members of Iran's Quds force on a mission to stir up trouble. Iran says the men were diplomats.
 
It has developed into one of Iran's main complaints against the US, provoking fierce debate when the two sides held talks in Baghdad last month.
 
Al-Maliki promised the families that he would work for the detainees' release.
 
When asked whether he thought al-Maliki shared his views on Iran, Bush said: "So the first thing I looked for was commitment against the extremists.
 
"The second thing is 'does he [al-Maliki] understand with some extremist groups there's connections with Iran', and he does. And I'm confident.
 
'Price to pay'
 
"Now, is he trying to get Iran to play a more constructive role? I presume he is. But that doesn't - what my question is - well, my message to him is, is that when we catch you playing a non-constructive role there will be a price to pay."
 
The White House later clarified with Al Jazeera that Bush was referring to Iran when talking about a price to pay.
 
Bush, who called Iran "a very troubling nation", said Tehran was "a destabilising influence" in the Middle East and warned that "there will be consequences" for any Iranians shipping weapons, including sophisticated roadside bombs, inside Iraq.
 
Bush suggested al-Maliki had been photographed smiling with his Iranian hosts, including Mahmoud Ahmadinejad, Iran's president, only as a diplomatic nicety.
 
"You don't want the picture to be kind of, you know, duking it out," Bush said, holding up his fists like a boxer.
 
It was the second time this week Bush has had to defend his tough stance against Iran with cautionary words to a key ally in the face of possible differences over Tehran's motives.
 
He warned Hamid Karzai, the Afghan president, on Monday during a visit to the US presidential retreat at Camp David to be more suspicious of Iran after the Afghan leader had brushed aside US accusations that Tehran was arming the Taliban.
 
Iran, with a majority of Shia Muslims like Iraq, has been an important political player in Iraq since the 2003 US-led invasion.
 
Tehran denies Washington's accusations that it is supplying weapons to fighters to fuel violence, and instead blames the US military presence.
 
Baghdad has urged both countries to negotiate and not fight out their differences on Iraqi soil.