The demonstration on the national holiday at the main square of Prague was called by far-right political movements, radical groups and the country's Communist party, the Prague Morning newspaper reported. Tens of thousands of people joined the rally, the newspaper said.
The protesters reportedly waved Czech flags, chanted slogans "Resign, Resign" and carried banners calling for a withdrawal from NATO and the European Union.
"This is a new national revival and its goal is for the Czech Republic to be independent," event organizer Ladislav Vrabel was quoted as saying by the Prague Morning.
A smaller-scale rally was held in another major Czech city of Brno, the report said.
"Russia is not our enemy, the government of warmongers is the enemy," one of the speakers said during the demonstration, the Prague Morning reported.
Western countries have imposed several packages of sanctions on Russia, including its energy sector, since the start of the special military operation in Ukraine on February 24. Disruption in supply chains has led to higher fuel and food prices across the EU and the United States, driving inflation to record levels and causing cost of living to soar.
The Czech Republic has been a staunch supporter of Ukraine, supplying heavy weapons to the Ukrainian army and hosting some 450,000 Ukrainian refugees, providing them with medical care, financial assistance, as well as work permits.