U.S. Senator Richard Lugar, one of several foreign envoys attending, hailed Zhvania as a sober force for democratic change.
Other envoys included Russian Transport Minister Igor Levitin, and World Bank President James Wolfensohn.
Georgian President Mikheil Saakashvili, who has taken over Zhvania's duties until a new government is formed, declared 5 February and today days of national mourning.
Officials say the 41-year-old died from carbon monoxide poisoning caused by an improperly ventilated gas space heater in the Tbilisi apartment of a friend, who also died.