The pledges came as al-Maliki met in Tehran with Iranian President Mahmud Ahmadinejad, national security chief Ali Larijani, and other top Iranian officials.
Al-Maliki reportedly told Ahmadinejad that he appreciated what he called "Iran's positive and constructive stance" toward Iraq.
Ahmadinejad expressed optimism that Iraq would someday achieve stability and security. But he said both Iran and Iraq have a "heavy burden" before then.
The United States accuses Iran of contributing to instability in Iraq by training and arming militants fighting there.
Iran's First Vice President Parviz Davudi meanwhile has said Iran and Iraq will soon sign an agreement on building an oil pipeline between the two countries.
Davudi, speaking after talks with al-Maliki, said the pipeline would carry oil from Iraqi oilfields to refineries in Iran.
He said Iraq's Oil Minister, Hussain al-Shahristani, is due to visit Tehran to discuss the deal "in coming days."
(compiled from agency reports)