On Wednesday, US banking giant Citi, consultancies Deloitte and PwC, as well as other firms closed their offices or told employees to leave, mainly in the Dubai International Financial Centre (DIFC), sources told AFP.

Iran's threats sparked concern at the heart of the Middle East's top financial hub, home to international companies and multi-billion dollar businesses.

Two witnesses described seeing damage to a building in DIFC after hearing loud bangs. Dubai's media office confirmed that the facade of a building in "central Dubai" had been hit by debris from a successful interception.

An AFP correspondent also saw the damaged building in DIFC after hearing the bangs.

"I jumped out of bed -- that was the loudest sound I've ever heard," one of the witnesses living close by told AFP, requesting anonymity.

"It was so loud, I was so sure when I looked out the window that it was going to be something catastrophic... The ground shook," they added.

Another AFP correspondent described hearing a huge double blast that rattled buildings and left a large cloud of black smoke hanging over the central district.

On Thursday, a drone fell near DIFC, a day after Tehran threatened to hit US and Israel-linked banks and other economic targets following a reported attack on a bank in Iran.

The United Arab Emirates' air defences have intercepted more than 1,500 Iranian drones and nearly 300 missiles during the Middle East war -- by far more than any other country hit by Iran.

Nasser Saidi, a former Lebanon minister and former chief economist at the DIFC Authority, told AFP that DIFC played a "strategic role" in Dubai's long-term economic plan and that was all the more important in the current climate.

"DIFC has transitioned from a regional hub to a top-tier global financial capital," he said.

"The ongoing conflict highlights the necessity of a neutral, soundly regulated and operationally resilient hub," he added.

Iran has taken aim at US assets but also civilian infrastructure including landmarks, airports, ports and oil facilities around the Gulf after US-Israeli attacks decimated its leadership.

The Gulf has borne the brunt of Iran's attacks since the Middle East war began, with 24 people killed in the region including seven US service members and 11 civilians.