The commander of the elite Quds force of Iran's Revolutionary Guard, Qassem Suleimani, met with Nasrallah and attended the funeral ceremony of Jihad Mughniyeh, a Hezbollah fighter who was killed in an Israeli air strike in Syria last week.
Iran's semi-official Fars News Agency reported the meeting, citing Lebanese TV channel Al Mayadeen, but did not provide any details about their discussions.
On Tuesday, Iranian Deputy Foreign Minister Hossein Amirabdollahian warned Israel by sending a diplomatic message through the United States, saying "they crossed our red lines", in reference to a Jan. 18 Israeli air strike on the Syrian-controlled area of the disputed Golan Heights.
The airstrike killed a senior Revolutionary Guard commander Mohammad Ali Allahdadi and six Hezbollah fighters including Jihad Mughniyeh, the son of Imad Mughniyah, a Hezbollah leader killed by a car bomb in Syria in 2008.
"We told the Americans that the leaders of the Zionist regime should await the consequences of their act," said Amirabdollahian, according to Iran's Islamic Republic News Agency.
Two Israeli troops were killed and seven others wounded on Wednesday when Lebanon's Hezbollah movement attacked two Israeli military vehicles in the Israeli-occupied Shebaa Farms region, which is claimed by Lebanon.
Iran has 'strong desire' to mend ties with Saudi:
Iranian lawmaker Alaeddin Boroujerdi said his country had a "strong desire" to strengthen ties with regional rival Saudi Arabia.
"Iran has a definite, firm desire to build good, strong relations with Saudi Arabia," Boroujerdi, who is currently visiting Beirut, said at a joint press conference in Beirut.
Boroujerdi, who heads the Iranian parliament's national security and foreign relations committee, also expressed Iran's keenness to improve ties with Lebanon.
Boroujerdi also met with Lebanese Prime Minister Tammam Salam during his visit to Beirut.
Boroujerdi, who arrived in the Lebanese capital on Thursday, is scheduled to attend a Friday ceremony organized by the Shiite Hezbollah movement to commemorate fighters killed in what Hezbollah and Iran say was an Israeli drone strike in the Syrian town of Quneitra earlier this month.
For over two years, Hezbollah, an ally of Tehran, has been openly engaged in the conflict in Syria, where it continues to fight alongside Syrian regime forces.
In 2006, Israel and Hezbollah fought a 34-day war in which more than 1,200 Lebanese – mostly civilians – were killed by devastating Israeli bombardments of southern Lebanon.
Some 160 Israelis, mostly soldiers, were also killed in the conflict.