Police in riot gear on Monday clashed with anti-government demonstrators outside the Parliament buildings in the Georgian capital, Tbilisi.
Water cannons were fired on the crowds as authorities attempted to break up a second day of wide-spread rallies.
The protests were sparked last week when the Georgian Parliament failed to pass a draft constitutional amendment, which would change the electoral system to proportional representation.
The move had been promised by the governing Georgian Dream party in the wake of massive demonstrations in June.
Hundreds of police were deployed outside the Parliament buildings and the Interior Ministry confirmed that 18 people had been arrested.
Demonstrators had vowed to prohibit anyone entering the Parliament until their demands for snap elections are met.
Despite authorities later setting up artificial barriers in front of parliament, a group of protesters remained to give speeches and continue chants of "Long live Georgia".
The violence broke out a day after 20,000 people rallied in the centre of Tbilisi, in the largest anti-government demonstrations in the country since 2012.
In a joint statement, the EU delegation in Georgia and the U.S. Embassy said they recognised "the deep disappointment of a wide segment of Georgian society" at Parliament's failure to pass constitutional amendments.
They called on the Georgian government and all political parties to work together and "restore trust through a calm and respectful dialogue".
Opponents say the current electoral system unfairly favours the Georgian Dream party, which holds a strong majority in the legislature.
But the party's general secretary and Tbilisi Mayor Kakha Kaladze flatly ruled out the possibility of early polls on Monday.
In a lengthy post on Facebook, the Georgian Dream party accused the opposition of "destabilising political processes with cheap and destructive performances."
"The elections will be held in the manner prescribed by the current constitution, within the prescribed timeframe."
"We urge our opponents to prepare for the elections and not blame the electoral systems for the lack of people's support."
Proportional representation is due to be introduced in Georgia in 2024, but there are fresh calls for changes to be made ahead of next year's parliamentary elections in October.
Click on the player above to watch Matthew Holroyd's report in The Cube.