Nuri al-Maliki, Iraq's incumbent prime minister, has told army officers that they should not intervene in the country's political crisis.
The armed forces and security services must limit their role to defending the country, Maliki told a meeting of senior army, police and security officers on Tu esday.
His comments came a day after Iraqi President Fouad Massoum selected Haider al-Abadi, the deputy speaker of parliament, to replace Maliki as prime minister.
The president gave Ibadi 30 days to present a new government to lawmakers for approval.
Abadi's nomination quickly received support from the Iraqi Kurdistan leader Masoud Barzani, Iran and the United States as well as Saudi Arabia, prompting Maliki to describe the nomination as a 'violation of the constitution'.
Barzani told Joe Biden, the US vice president, that he would be willing to work with the new Iraqi leader.
But Maliki insists that he is entitled to form the next government, and has also stressed that any violation of the constitution must be prevented.
It will be up to the judiciary to remedy the violation in line with decisions of the Federal Supreme Court, Maliki said.
Al Jazeera's Jane Arraf, reporting from Erbil, said that it was clear that the support was going to the PM designate.
Without any question, we are prepared to consider additional political, economic and security options as Iraq starts to build a new government
On the question over Maliki's claims that the nomination violated the consitition, Arraf said the "problem with the constitution is that it is quite flexible and many people have different interpretations."
On Tuesday, Secretary-General Ban Ki-moon said it was "imperative'' that Iraqi security forces stayed out of the political process leading to the formation of a new government.
Meanwhile, US Secretary of State John Kerry urged Iraq's new leaders to work quickly to form an inclusive government and said the US was now prepared to offer the new government significant additional aid in the fight against the Islamic State group.
Kerry said the US "stands ready to fully support a new and inclusive Iraqi government'' and called on Prime Minister designate Haider al-Ibadi "to form a new cabinet as swiftly as possible.''
According to Kerry, Washington would be ready "to fully support a new and inclusive Iraqi government, particularly in its fight against ISIL."
"Without any question, we are prepared to consider additional political, economic and security options as Iraq starts to build a new government,'' Kerry said.
Kerry would not outline the potential new US assistance to Iraq, but he ruled out the return of American combat troops to the country.
Defence Secretary Chuck Hagel said the Pentagon was considering additional aid to the Iraqi security forces, including the Kurdish army, which is now involved in heavy fighting against the armed rebels.
The Obama administration has begun directly providing weapons to Kurdish forces who have started to make gains against the Islamic State, senior US officials said, but the aid has so far been limited to automatic rifles and
On Tuesday, at least 12 people were killed in two bomb blasts in the Baghdad, raising fears of further political violence in the capital.