US Central Command (CENTCOM) said on X the operation on Sunday night targeted military command centres, air defence and coastal surveillance facilities, missile and drone launch sites and communications networks.
CENTCOM said the operation aimed to further degrade military capabilities that Iran has used to attack commercial shipping and civilian mariners in the Strait of Hormuz.
The US has also reported its highest military death toll in months over the past week.
On Saturday, the US military announced the deaths of two service members in Iranian attacks, the first such fatalities reported since the early days of the conflict.
On Sunday, CENTCOM said another US service member had died on Saturday in northern Iraq while disposing of unexploded ordnance from a downed Iranian one-way attack drone, bringing the confirmed US military death toll in the conflict to 17.
"We hit them very hard again tonight," US President Donald Trump told reporters after attending the FIFA World Cup final.
"And we did that in honour of the" slain soldiers.
Following the start of the latest wave of strikes, media in Iran reported explosions in several parts of the country.
According to the country's Tasnim news agency, explosions were reported in the northern city of Tabriz, the port city of Chabahar on the Gulf of Oman, Konarak in the south-eastern province of Sistan-Baluchestan, the port city of Mahshahr in Khuzestan province and the Gulf port of Bandar Imam Khomeini.
Meanwhile, Tehran continued retaliatory attacks on countries hosting US military bases, with Kuwait saying early on Monday that its air defences intercepted hostile drones launched from Iran.
Air raid sirens also sounded again in Bahrain, another US ally that hosts US military forces, the country's Interior Ministry said.
The Islamic Revolutionary Guard Corps said two oil tankers had exploded and been immobilised after attempting to transit what it described as an unsafe southern route through the Strait of Hormuz, alleging they had been encouraged by the US military to use the passage.
Reuters could not immediately verify the incident. The statement gave no details on the vessels' names, flags, crews or any casualties.
The Guards said the waterway would remain unsafe as long as what it called US "aggression" in the region continued, warning that "this passage will not be safe for the transit of petrochemical products, nor even a single drop of oil and gas".
They told the US military to prepare for a "punitive operation".
The escalating conflict has heightened risks to shipping in the Strait of Hormuz.
Early on Monday, the UK Maritime Trade Operations (UKMTO) said a vessel was on fire in the waterway, adding that the cause of the blaze was not immediately clear.
The incident occurred about eight nautical miles north-west of Kumzar, Oman, UKMTO said in an advisory.
It advised vessels transiting the area to exercise caution while it investigated the incident.
Washington is deploying additional fighter jets and aerial refuelling aircraft to the Middle East in response to the latest escalation, according to US media reports.
The conflict over the strategic waterway, a key route for global energy supplies, has escalated again since the start of the month.
with reuters and AP
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