Despite daily protests President Saakashvili insists he will not resign
Several people have been injured as opposition protesters clashed with police during a rally outside the Georgian parliament in Tbilisi.
A police spokesman said three officers were stabbed and six others wounded by a gang wielding sticks and knives.
The opposition denied the report, saying some 20 plainclothes police had attacked its supporters with batons.
Hours before the violence the Orthodox Church urged the government to hold snap elections or negotiate.
Patriarch Ilia II said the situation in Georgia was explosive and that the authorities had to take active steps to reduce tension.
He also denied that comments he made earlier this week were intended to show support for the government.
The BBC's Tom Esslemont in Tbilisi says it is impossible to know who is to blame for starting Thursday's clashes - the first significant outbreak of violence since 6 May, when several dozen people were injured outside a police station.
But what is certain, our correspondent says, is that tensions have increased in the capital.
Ever since these protests began seven weeks ago, the government has said it would not allow police to intervene lest they provoke street violence such as that which brought about a state of emergency in November 2007, he adds.
However, most of the opposition party leaders have continued their daily calls for President Mikhail Saakashvili to resign over his mishandling of the war with Russia last year and his alleged restriction of democratic rights.
Our correspondent says they have instead sought to refresh their tactics to attract a wider following.
After filling Dynamo Tbilisi's 60,000-seat football stadium during a rally marking Georgia's independence day on Tuesday, some opposition supporters sat across railway lines blocking them for three hours.
But, as a result of the ongoing near daily demonstrations, life is being made increasingly hard for residents of the capital, some of whom are now calling for them to end, our correspondent adds.