Iran's central military command announced on Saturday that it had once again closed the vital Strait of Hormuz over Israel's attacks on southern Lebanon, describing them as a breach of Tehran's agreement with the US.
"It is hereby announced that the Strait of Hormuz will be closed to vessel traffic; It is noted that this first step is a response to the enemy's breach of promise, and if the aggression continues, further steps will be planned and taken to force the enemy to comply with its obligations," said the Khatam-al Anbiya Central Headquarters in a statement carried by state TV.
Lebanese state media reported Israeli air raids on around 20 locations, with the country's civil defence agency saying 16 people were killed in the Nabatieh area.
US President Donald Trump and his Iranian counterpart Masoud Pezeshkian this week signed a preliminary agreement to halt the Middle East war on all fronts, including Lebanon -- a key demand of Tehran's.
But follow-up talks scheduled for Friday in Switzerland were indefinitely postponed as Israel launched a wave of strikes in Lebanon that left dozens of people dead while four of its soldiers were killed in combat, sparking a furious reaction at home.
On Friday afternoon, a US official announced a new ceasefire between Israel and Hezbollah brokered by US and Qatari mediators, with Israel's ambassador to Washington saying it would respect the truce if Hezbollah did.
But on Saturday an Israeli military official said it was conducting fresh attacks against the Iran-backed movement, which it accused of having "launched more than 50 projectiles at Israeli forces in southern Lebanon" overnight.
Hezbollah has not officially claimed any attacks on Israel or its troops in Lebanon since the ceasefire was announced.
Hezbollah lawmaker Hassan Fadlallah said Saturday that his group insisted "that the enemy fully and comprehensively respects the ceasefire."
"The resistance has the full right to confront this enemy when it attacks us, as it is the aggressor and the occupier," he added.
An Israeli military official cited by public broadcaster Kan claimed his country's approach to the truce as being "on the basis of fire being answered with fire."
Lebanese authorities reported 47 people were killed in Israeli airstrikes on Friday, the highest toll since the US and Iran struck their deal.