The opposition, who have been demonstrating in the capital for the past month, claim over 60 people, including six police officers, were injured in clashes at a police compound in Didi Digomi, a Tbilisi suburb on Wednesday night, 29 people were hospitalized.
"We are fighting for democracy, and we will not disperse until we see President Mikheil Saakashvili resign," said Nino Burdzhanadze, ex-parliamentary speaker, who heads the Democratic Movement-United Georgia.
The clashes occurred when demonstrators tried to climb the fence of a police compound on Wednesday evening, Interior Ministry spokesperson Shota Utiashvili said police used batons to disperse the protestors.
Among those reported injured are: Levan Gachechiladze, an opposition leader, Giya Maisashvili, the Party of the Future leader, Shalva Ogbaidze from the Democratic Movement-United Georgia party and a number of other opposition activists.
Gachechiladze's brother, pop singer Giorgi, is reported to be in a critical condition.
Opposition demonstrators, 1,000s of whom gathered in front of the country's parliament building last night, are demanding that Saakashvili resign.
"We have no way back. Either we stop this lawlessness in the next few days, or we die. This is a fight to save our families," said Giorgi Khaindrava, an opposition leader.
The opposition pledged to bring all Tbilisi residents onto the streets on Thursday.
Three youth movement activists detained for causing last night's clash with the police have been released, the Rustavi-2 TV channel said citing prosecutors.
The Georgian Interior Ministry is expected to make a statement shortly.
The country's patriarchate described the situation in Tbilisi as highly charged and urged everybody to remain calm, also calling for the authorities to introduce measures as soon as possible to ease tensions.
However, Saakashvili has no plans to cancel a visit to the EU Eastern Partnership summit in Prague on Thursday, a presidential spokesman said.
"The president's trip to Prague has not been cancelled. He will go as scheduled," the spokesman said.