The elite Guards fired seven medium-range ballistic missiles at the headquarters of the Kurdistan Democratic Party of Iran in Koysinjaq in Iraq's autonomous Kurdish region, causing major casualties and damage with what they described as a precision strike.

"With a range of 2,000 kilometres (1,200 miles), our missiles endow the Iranian nation with a unique ability to fight against arrogant foreign powers," Guards commander Major General Mohammad Ali Jafari told the semi-official ISNA news agency.

"All those that have forces, bases and equipment within a 2,000 kilometre radius of Iran's sacred borders should know that (our) missiles are highly accurate."

Iranian officials have long referred to the United States as the "world arrogance" and the Guards' arsenal of medium-range missiles puts US bases in the Gulf and beyond within reach.

Relations between Iran and the United States have nosedived since President Donald Trump abandoned a landmark nuclear agreement in May and reimposed crippling sanctions in a major blow to its already struggling economy.

"(Our) recent vengeance upon terrorists had a very clear message for enemies, especially superpowers who think they can bully us," said Jafari.

The KDPI had sent numerous "terrorist teams" into Iran's West Azerbaijan, Kurdistan and Kermanshah provinces in recent months, according to the Guards.

The group is Iran's oldest Kurdish movement and several of its leaders have been assassinated by Tehran in the past.

Iran's ballistic missile programme is a bone of contention, particularly for Washington, which has repeatedly accused Tehran of seeking to destabilise the region.

Tehran says its missile arsenal is vital to its defence in a troubled region.