"The new US policy on the ground toward the IS is still 'duplicitous'," Press TV quoted Iran's Deputy Foreign Minister for Arab and African Affairs, Hossein Amir-Abdollahian, as saying.
His remarks came after the US House of Representatives approved President Barack Obama's strategy to train and arm "moderate" militants in Syria to tackle the threat of the IS militant group.
The Pentagon plans to train and arm 5,000 militants in Syria as part of the Obama administration's long-term strategy to confront IS.
"They want to play with the IS in Iraq, and provide opportunities for IS in Syria," Amir-Abdollahian said.
"Arming moderate militants in Syria is a strategic mistake and is indeed double standards and considered as the escalation of insecurity and boosting of terrorism," he added.
The security situation in Iraq began to deteriorate drastically after June 10, when bloody clashes broke out between Iraqi security forces and hundreds of IS militants.
The militants have taken control of the country's northern city of Mosul and seized swathes of territories after the Iraqi security forces abandoned their posts in Nineveh and other Sunni-predominant provinces.
The extremist group has committed heinous crimes and threatened all communities, including Shias, Sunnis, Kurds, Christians and Yazidis, during its advances.