President Barack Obama's plan to send advisers to Iraq to help Baghdad counter Sunni Islamist militants shows the US is not serious about fighting terrorism, an Iranian official was quoted by official media as saying.

Obama on Thursday offered up to 300 Americans to help co-ordinate the fight against Islamic State of Iraq and the Levant (ISIL). But he held off granting a request for air strikes from the Shi'ite-led government and renewed a call for Prime Minister Nuri al-Maliki to do more to overcome sectarian divisions that have fuelled resentment among the Sunni minority.

"Obama's recent remarks showed that the White House lacks serious will for confronting terrorism in Iraq and the region," the official IRNA news agency reported Deputy Foreign Minister for Arab and African Affairs Hossein Amir Abdollahian as saying.

Abdollahian said the US "delay" in fighting terrorism and the ISIL has "fuelled suspicions and doubts about the US objectives in Iraq," IRNA reported.

Another official, Hamid Aboutalebi, who works in the office of President Hassan Rouhani, also criticsed Obama's remarks.

"The US cannot adopt contradictory policies in the Middle East; to support war in Syria and peace in Iraq or be on the side of terrorists in Syria and against them in Iraq," Aboutalebi wrote on his Twitter account.

Iraqi forces were massing north of Baghdad on Friday, aiming to strike back at the Islamists' offensive towards the capital.

Mohammad Nahavandian, Rouhani's chief of staff, said Iran was closely watching developments in Iraq and would give an "appropriate" response to a request from Iraq for intervention to solve its internal problems, IRNA reported.

"We are concerned about the fate of sacred (Shi'ite) sites particularly," he was quoted as saying by IRNA, echoing a June 18 remark by Rouhani that Iranians were ready to go to Iraq to protect such sites if need be.

Nahavandian however blamed what he called a history of foreign intervention for Iraq's predicament. He also said that if more effective attempts had been made to stop the war in Syria, the violence there would not have spread to Iraq.-Reuters