Dozens were killed and several thousand were wounded when Hezbollah communication devices exploded Tuesday and Wednesday.
Hezbollah leader addressed his supporters following the 'double-blasts', calling it a 'major blow' to the group, but one that has not brought them to their knees.
The UN Security Council will convene on Friday to discuss the recent explosions.
UN High Commissioner for Human Rights Volker said in a statement that the blasts in Lebanon may violate international humanitarian law.
UK foreign secretary David Lammy has asked British nationals to leave Lebanon, amid rising tensions following two days of Israeli-suspected attacks on Hezbollah.
"My message to British nationals in Lebanon is leave while commercial options remain. Tensions are high and the situation could deteriorate rapidly," Lammy posted on X (formerly Twitter).
The US Defense Secretary Lloyd Austin has postponed his trip to Israel amid the escalation on the Israeli-Lebanese border, according to Axios.
The US Secretary of State Antony Blinken warned against escalation in the Middle East following two days of suspected Israeli attacks on Hezbollah that saw the group’s communication devices explode.
“We don’t want to see any escalatory actions by any party,” Blinken said after talks in Paris with French counterpart Stephane Sejourne.
He called for restraint and asked all regional players not to endanger a potential ceasefire in Gaza.
Iran’s Revolutionary Guards commander Gen. Hossein Salami sent a message to Hezbollah leader Hassan Nasrallah, according to Iran’s official news agency, IRNA, saying that Israel will face a ‘crushing response’ from the Resistance Front –a name given to Iran’s allied armed groups across the Middle East.
Salami called the explosion of communication devices in Lebanon a “terrorist crime” and a sign of “desperation”.
“There is no doubt that the Israeli aggression that took place on Tuesday and Wednesday with the bombing of the pagers is major and unprecedented aggression that will be met with a severe reckoning and just punishment."
"The enemy also aimed, through the massacres of Tuesday and Wednesday, to strike (our) infrastructure and command and control structure and to spread a state of weakness and confusion in the leadership of Hezbollah. This never happened even for a single moment."
"What happened did not affect our determination, our command and control structure, our readiness or our presence on the fronts. Rather, it will increase our strength and presence."
"What happened is a genocide and a major massacre to be added to the major massacres committed by the enemy since the creation of this cancerous tumor in our region," Nasrallah said.
"It can be called a declaration of war", he added.
"There is no doubt that we have been exposed to a major and unprecedented blow on the security and humanitarian levels," Nasrallah told supporters via video link
Hezbollah leader thanked all those who helped treating the wounded, praising the Iranian government in particular for transferring and treating some in Iran.
This has been a point of controversy in Iran as some Iranians have criticized the government for its "double standard", injuring and blinding protesters while bringing in Hezbollah members for treatment.
Hassan Nasrallah starts by saying he wanted to speak on the one-year anniversary of the October 7, but had to change plans after the recent events.