The Iranian Supreme Leader Ayatollah Ali Khamenei has called Israel the "common enemy" of Muslim nations.
The 85-year-old cleric spoke as he led Friday prayers in Tehran for the first time in four years.
He called on Muslim nations to "strap the belt of defense" from Afghanistan to Yemen and from Iran to Gaza and Lebanon.
Beirut came under renewed bombardment from the Israeli military overnight as it continued its war against Hezbollah.
The southern suburb of Dahiye, a stronghold of the Iran-backed terror group, was hit around midnight after Israel ordered people to leave their homes in some areas, according to residents.
Huge explosions also rang out near Beirut's main airport in the early hours of Friday.
Iran’s Foreign Minister Abbas Araghchi arrived in Beirut on Friday for talks with Lebanese officials about the battle between Israel and Hezbollah.
Tehran is Hezbollah's biggest backer and has funneled billions of dollars and weapons to the terror group over the years.
Araghchi arrived in Lebanon as Israel launched further strikes on different parts of the country, including Beirut’s southern suburb, south Lebanon, and the eastern Bekaa Valley.
An Israeli airstrike near Lebanon's Masnaa border crossing with Syria cut off a road used by hundreds of thousands to flee the recent fighting, according to the Lebanese Transport Minister Ali Hamieh.
Hamieh told Reuters the strike hit inside Lebanon, near the crossing, creating a 12-foot-wide crater.
The Israel Defense Forces (IDF) accused Hezbollah on Thursday of using the crossing to transport military equipment into Lebanon.
Thursday saw fighting between the Israel Defense Forces (IDF) and Hezbollah intensify in Lebanon.
The Israeli military struck closer to the center of the capital city of Beirut than it has in years, hitting an apartment, which resulted in the deaths of nine people.
The IDF also claimed to have taken out targets linked to Hezbollah's intelligence headquarters in Beirut and to have killed the commander from the terror group behind the July rocket attack on a football pitch in the Golan Heights which killed 12 children.
President Joe Biden revealed he's discussed the possibility of Israeli forces striking Iranian oil facilities, in retaliation for the Oct. 1 Iranian ballistic missile barrage against Israel.
Biden spoke to members of the press on the White House South Lawn before boarding the presidential helicopter, Marine One, on Oct. 3. One reporter asked Biden if he would support Israel striking Iranian oil facilities.
"We’re in discussion of that," Biden began his reply before trailing off. "I think—I think that would be a little—anyway."
President Joe Biden joined with leaders from the rest of the Group of Seven (G7) nations—Canada, France, Germany, Italy, Japan, and the United Kingdom—in expressing their dismay at Iran's Oct. 1 ballistic missile salvo targeting Israel.
"We, the Leaders of the G7, express deep concern over the deteriorating situation in the Middle East and condemn in the strongest terms Iran’s direct military attack against Israel, which constitutes a serious threat to regional stability," the G7 leaders said in a joint statement on Oct. 3.
The G7 countries reiterated their support for Israel's security and "discussed coordinated efforts and actions to avoid escalation in the area."