Nabih Berri, the Lebanese parliament's speaker, said in a statement: "The consultations are delayed until November 6 because of the absence of several leaders."
An-Nahar newspaper quoted Berri as expressing "concern that important officials be present", referring to Amin Gemayel, the Maronite leader and former president, Walid Jumblatt, the Druze leader, and Saad al-Hariri, the parliamentary majority leader.
Berri, a Shia Muslim leader with close links to Hezbollah, had asked politicians to begin up to 15 days of talks on October 30 to discuss calls for a national unity government and a new election law.
Hezbollah has been calling for changes to the government since the month-long war with Israel ended in August.
Coalition members who are opposed to the Syrian government and who dominate the government of Fuad Siniora, the prime minister, have dismissed the demand, prompting Hezbollah and its allies to threaten street protests.
The coalition, which supports international calls for the disarming of Hezbollah, has a majority in parliament, but Siniora's 24-member cabinet also includes five ministers from Hezbollah and Berri's Amal group.
Hezbollah wants more of its allies included, especially Michel Aoun, a Christian opposition leader, and pro-Syrian groups.
Roundtable talks arranged by Berri in March were abandoned in June with no concrete decisions reached.
The talks had been called to find an agreement on what to do about Emile Lahoud, the pro-Syria president. The anti-Syria majority has demanded his departure after his mandate was controversially extended for another three years in 2004, in accordance with Damascus's wishes.