Thousands gathered in Tehran on Monday to mourn the loss of assassinated Hezbollah leader Hassan Nasrallah and protest against Israel for its ongoing military campaigns in Lebanon and Gaza.

Footage shows crowds chanting anti-Israel and anti-US slogans while waving Hezbollah and Palestinian flags. Protesters are seen holding portraits of Nasrallah and slain Iranian General Qasem Soleimani, who was killed in a US airstrike in 2020.

On Friday, an Israeli airstrike hit Hezbollah's headquarters in Beirut's southern suburbs, killing the militant group's leader Hassan Nasrallah and others.

"We expect officials from the Islamic Republic of Iran to take severe revenge on Israel as their priority and surprise Israel," a demonstrator said.

"God willing, all the blood of the oppressed people that have been spilt during this time in Lebanon and finally led to the martyrdom of Seyyed Hassan Nasrallah be responded to," he added.

The IDF's latest campaign of airstrikes began last Monday, with more than 1,030 killed and 6,300 injured in total, according to the Lebanese Health Ministry.

The Israeli military announced on Monday that it was undertaking 'limited' and 'targeted' ground raids against Hezbollah in southern Lebanon.

Tensions had since escalated following the assassination of Nasrallah, confirmed by the group after a large-scale Israeli airstrike on Beirut on Friday.

Last week, the IDF announced the start of a campaign of airstrikes on Hezbollah positions dubbed 'Operation Northern Arrows'. The Lebanese Ministry of Health reported that these attacks have resulted in more than 1,800 deaths and 8,400 injured at the time of publication.

Hezbollah has been exchanging cross-border shelling with the Israeli forces since the outbreak of the war in Gaza.