The United States targeted bridges in Hormozgan province and a surveillance tower at Chabahar port.
US has tightened its naval blockade on Iranian ports and stepped up strikes on strategic infrastructure.
Shipping through the Strait of Hormuz continues to decline amid escalating military exchanges.
The United States struck bridges and a key port in southern Iran early on Friday, expanding its air campaign against critical infrastructure as President Donald Trump sought to pressure Tehran to end its blockade of the Strait of Hormuz.
In response, Iran launched fresh missile attacks on several US-allied countries in the Middle East, including Qatar, a key mediator in the conflict.
The latest escalation comes after the collapse of a temporary ceasefire agreed last month. Since then, the US and Iran have exchanged near-daily attacks as both sides vie for control of the strategic waterway. Iranian officials said the latest US strikes killed dozens of people and wounded hundreds more, with additional casualties reported on Friday.
The conflict began on February 28, when the US and Israel launched military operations against Iran. Tehran subsequently moved to effectively close the Strait of Hormuz to commercial shipping, sending global oil prices soaring and strengthening its leverage in negotiations.
Addressing the nation in a prime-time speech, Trump defended the military campaign.
"We are likewise winning big in Iran, and you will see the fruits of that labor very, very shortly," Trump said.
Overnight US airstrikes hit bridges in Iran's southern Hormozgan province, killing at least seven people, according to Iranian state television. The attacks struck Bandar Khamir, a coastal city on the Strait of Hormuz.
The highway and railway bridges appeared to be targeted to disrupt access between Bandar Abbas, Iran's largest port, and the country's central regions, including the capital, Tehran. While alternative routes remain open, the strikes could hamper the movement of military supplies as well as civilian goods across the country.
The US military's Central Command said it struck dozens of targets during the operation, which concluded at dawn on Friday, marking the sixth consecutive night of American airstrikes.
The strikes also brought down a surveillance tower at Iran's Chabahar port.
US Defence Secretary Pete Hegseth later shared footage of the tower collapsing. Iranian state media confirmed a third round of strikes on Chabahar port but did not immediately acknowledge the collapse of the tower.
Iran retaliated by firing missiles at Qatar, prompting authorities there to issue two public shelter warnings as air defence systems intercepted incoming projectiles.
Qatar, alongside Pakistan, has been mediating efforts to end the conflict.
Iran also launched missiles towards Bahrain and Kuwait early on Friday. Jordan's military said it intercepted three Iranian missiles, while explosions were reported in Irbil and Sulaymaniyah in Iraq's Kurdish region.
The latest strikes follow Trump's renewed threats to target Iranian infrastructure, including power stations and bridges, in an effort to force Tehran to loosen its grip on the Strait of Hormuz.
The US has also reimposed a naval blockade on Iranian ports to disrupt the country's crude oil exports.
(inputs from AP)
