Iran's defence minister has confirmed a Pentagon statement that two Iranian fighter jets fired on an unarmed US Predator drone in the Gulf last week, according to Al Jazeera.

"Last week an anonymous plane entered the space over the territorial waters of the Islamic Republic of Iran in the Persian Gulf area which, due to the timely, clever and decisive action of our armed forces, was forced to flee," Ahmad Vahidi was quoted by ISNA as saying on Friday, November 9.

The Pentagon on Thursday said the Iranian planes fired on the drone in the Gulf last week and missed, warning that the US stood ready to protect its forces in the region.

The incident occurred on November 1, less than a week before the US presidential election, the US Department of Defence said.

"They intercepted the aircraft and fired multiple rounds," spokesman George Little told a news conference on Thursday.

The exchange is the latest episode between the two countries amid a mounting crisis over Tehran's nuclear programme and a shadow war marked by cyber-attacks and assassinations in Iran.

Tough new sanctions led by the US are squeezing Iran's economy while Washington is accused of staging cyber sabotage on Tehran's uranium enrichment plants.