Many former Hezbollah supporters in the Arab world soured on the Iran-backed group when it entered the war in support of the authoritarian government of President Bashar al-Assad, whose violent crackdown on political protests in 2011 turned into a brutal six-and-a-half-year civil war that has displaced more than 11 million Syrians.
The Syrian government’s counterinsurgency crackdown included bombing and besieging Palestinian refugee camps, where there was some support for the Syrian rebels. That, too, led Palestinian and other Arab critics to complain that Hezbollah had strayed from its roots of resisting Israeli occupation and abetted in the oppression not only of Syrians, but also of Palestinian refugees in Syria.
Hezbollah is still believed to have thousands of troops in Syria, and Mr. Nasrallah, who spoke from an undisclosed location, made no suggestion that they would leave anytime soon.
On Monday, demonstrators marched down a road in the southern Beirut neighborhood that houses Hezbollah’s headquarters, chanting “Death to Israel! Death to America!” and “Zionists must die, die, so Jerusalem doesn’t die!”
Both the Israelis and Palestinians claim Jerusalem as their capitals. Israel captured East Jerusalem in 1967 and annexed it in a move that was never officially recognized by the international community.
Although Israel controls the entire city, both sides agreed in 1993 that its status would be resolved through peace negotiations. Critics, including many Palestinians, say Mr. Trump’s recognition of Jerusalem as Israel’s capital derails that process, which was already stagnant.
Alaa Dahab, a half-Palestinian, half-Lebanese teenager who grew up in Gaza, attended the rally on Monday to show her support for Hezbollah.
“We are with anyone that loves, helps and resists for Palestine,” she said.
The rally included a diverse group of people of varying ideologies, religions and nationalities — Islamists and communists, Muslims and Christians, Palestinians and Lebanese. Palestinian refugees were bused from refugee camps around Lebanon in what has become a staple in a week of protests against the Jerusalem decision.
Mirna Mhawesh, 16, a Palestinian who traveled to the rally from the Shatila refugee camp, said, “We are here because we can’t do anything from here except show Palestinians inside Palestine that we’re with them.”