Macron, wearing a black tie in mourning and flanked by security guards, promised to send more medical and other aid to Lebanon, while those around him chanted "Revolution"
He shook hands and hugged Beirut residents as he toured on roads strewn with rubble and flanked by shops with windows blown out after Tuesday's blast.
A grade 12 student asked Marcon to help "topple" the current political system.
The president has said he would deliver "home truths" to a government that France and other Western donors have said must reform the country's politics and the economy.
Before the Beirut port blast, whose explosive force was registered hundreds of miles (kilometers) away, Lebanon was grappling with an imploding economy - its banks in crisis, currency in freefall and a mountain of climbing debt.