United Opposition, led by imprisoned opposition leader Yulia Tymoshenko's Fatherland party, called for the Monday protest, RIA Novosti reported.
"The united opposition is calling on all opposition forces and all those who are not indifferent to the country's destiny to come to the Central Electoral Commission building and protect their choice and the right of every Ukrainian to elect power," reads a statement issued by Front Zmin, part of the United Opposition.
Nearly 100 percent of ballots cast in the Oct. 28 election have been counted; President Viktor Yanukovych's ruling Party of Regions has received 30 percent, while the United Opposition has pulled in 25.5 percent.
"Today the authorities are impudently falsifying elections in the districts where opposition candidates have won. To falsify results in favor of ruling party candidates, the will expressions of dozens of thousands of citizens are being canceled," the statement said.