Several cabinet ministers also refused to meet Blair as he held talks with his Lebanese counterpart, Fuad Siniora.
One demonstrator interrupted a press conference being held by the two leaders, holding up a banner in front of the pair before she was bundled away by security guards.
Many Lebanese have been angered by Blair's refusal to call for an early ceasefire during the month-long conflict.
"Beirut is free, Blair out," chanted the protesters. Some carried placards reading "In the name of the Lebanese people: Thank you for destroying our homes, neighbourhoods and memories."
The country's most senior Shia cleric, Ayatollah Mohammed Hussein Fadlallah, accused Blair of supporting Israel.
Fadlallah said Blair was a "killer of children, women and the elderly" and should be declared "persona non grata" rather than welcomed to Beirut.
Blair had been due to meet parliament speaker Nabih Berri, an ally of Hezbollah, but an aide to the Shia Muslim leader said he had left on a private visit abroad.
The aide would not say whether Berri had deliberately snubbed Blair, but said his trip had been previously planned.
The two prime ministers were scheduled to discuss the UN truce in effect since August 14 and Britain's contribution to post-war reconstruction.
Blair began his Middle East tour in Israel on Saturday on a visit that analysts say is directed partly at countering criticism of his pro-US stance during the Lebanon war and partly at boosting his political legacy.
On Sunday, after meeting Mahmoud Abbas, the Palestinian president, Blair said the international community should deal with a unity Palestinian government if it broke with the policies of the boycotted Hamas-led administration.