The death toll from attacks on bridges in Iran's southern Bandar Khamir rose to seven, Iran's IRGC-affiliated Tasnim news agency reported on Thursday, according to Iran International.

Meanwhile, five bridges in Iran's Hormozgan province were struck in overnight and early Friday US airstrikes, the provincial governor's office said, as quoted by Iran International.

Detailing the operation, the US Central Command (CENTCOM) said American forces, including fighter aircraft, drones and naval warships, launched precision strikes on dozens of Iranian military targets. The targets included coastal surveillance and air defence sites, military logistics infrastructure and maritime capabilities.

"This was the sixth consecutive night of U.S. strikes against Iran," CENTCOM said in a statement.

"At the Commander in Chief's direction, CENTCOM is further degrading Iranian military capabilities and holding Iran accountable for recent attacks on commercial shipping," it added.

The command also said more than 50,000 US service members deployed across the Middle East remain "vigilant, lethal and ready."

UN urges de-escalation

Amid the escalating conflict, United Nations Secretary-General António Guterres on Wednesday expressed deep concern over the continuing military escalation in the Middle East following ongoing exchanges of strikes between the United States and Iran over control of the Strait of Hormuz.

The latest fighting has shattered an interim truce established under a Memorandum of Understanding signed by the two countries in June.

The agreement had sought to halt hostilities that erupted in late February after US-Israeli strikes on Iran and retaliatory attacks by Tehran across the Gulf region.

Calling for restraint, UN spokesperson Stéphane Dujarric said Guterres urged all parties "to take immediate steps for de-escalation and return to the path of dialogue and diplomacy."

"The Secretary-General reiterates that a return to full-scale hostilities would exact an intolerable toll on civilians and have catastrophic consequences for international peace and security and the global economy," Dujarric told reporters in New York.

Guterres also renewed his call for the full restoration of international navigational rights and freedoms in and around the Strait of Hormuz, one of the world's most strategically important maritime corridors for global oil and natural gas exports.

He stressed that the exercise of navigational rights and freedoms must be respected by all parties in accordance with international law.