The warning came as a former US intelligence analyst disclosed on Sunday that the United States have been planning a full-scale military campaign against Iran even before the March 2003 invasion of Iraq.
Richard Clarke and Steven Simon, who coordinated counterterrorism policy in the Clinton and Bush administrations, wrote in The New York Times on Sunday that "any United States bombing campaign would simply begin a multi-move, escalatory process".
They warned that Iran would first attack Persian Gulf oil facilities and tankers, which could cause oil prices to spike above $80 a barrel.
However more likely, Iran could use its terrorist network to strike American targets around the world, including inside the United States, Clarke and Simon said.
"Iran has forces at its command that are far superior to anything al-Qaeda was ever able to field," they wrote.
Their article argued that Iran was in a position to make the situation in Iraq far more difficult for the United States than it already is.
A report disclosed by a former US official on Sunday said that the US has been planning an attack against Iran since 2003.
William Arkin, who served as the US Army's top intelligence mind on West Berlin in the 1970s and accurately predicted US military operations against Iraq, said the plan is known in military circles as TIRANNT, an acronym for "Theatre Iran Near Term".
It includes a scenario for a land invasion led by the US Marine Corps, a detailed analysis of the Iranian missile force and a global strike plan against any Iranian weapons of mass destruction, Arkin wrote in The Washington Post.
Preparations under TIRANNT began in earnest in May 2003 and never stopped, he said. The plan has since been updated using information collected in Iraq.