According to media reports, a human chain stretched through the entire capital before protesters gathered in front of the parliament building.
Saturday's rally was initially peaceful, with protests also recorded in other cities, including Batumi, Kutaisi, Zugdidi, Poti, Rustavi and Gurjaani, local media reported.
Demonstrators formed a human chain outside the parliament building in Tbilisi. (EPA PHOTO)
The inauguration of the disputed new president of Georgia, Mikheil Kavelashvili, is set for Sunday despite weeks of protests.
The outgoing pro-Western head of state, Salome Zourabichvili, plans to prevent his inauguration as she does not recognise Kavelashvili's legitimacy.
Zurabishvili called on her supporters to gather in front of the presidential palace on Sunday.
"I am waiting for you in front of the Orbeliani Palace," she was quoted as saying by the NewsGeorgia agency.
She said she would then decide with her supporters how to proceed over the next few days.
For weeks, thousands of people have been demonstrating daily in Georgia for a return to the country's pro-EU policies and for a re-run of October's parliamentary election, which saw the nationalist ruling Georgian Dream party declare itself the winner.
Protesters fear the party is too close to Russia and will bring the country further into Moscow's orbit, decades after it won independence from the Soviet Union.
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