Ukrainian radicals lobbed fireworks at the Russian embassy in Kiev early Saturday, police said, a day before it was due to open as a polling station for Russia's parliamentary elections.
Video broadcast by Ukrainian media showed about 20 young men with a banner saying "Fireworks today, Grad (multiple rocket launchers) tomorrow."
On Sunday, Russian citizens in Kiev will be able to cast parliamentary ballots at the embassy and other diplomatic premises in Ukraine.
On Friday, the Kremlin said it was Kiev's responsibility to ensure the security of the election process.
"They (Ukraine) are obliged to do so in compliance with the Vienna Convention", President Vladimir Putin's spokesman Dmitry Peskov said.
But Ukrainian Prime Minister Volodymyr Groysman said his country "will not guard the electoral process of the Russian Federation. The law enforcement system will perform its functions in a normal mode."
Speaking at the annual Yalta European Strategy ("YES") conference in Kiev, he described the protest as "hooliganism" and "a small incident that does not require any comment."
Ukraine has repeatedly stated that it would not recognize the Russian elections in the Crimean peninsula, which Russia annexed in March 2014.
On Friday, the United States also said did not acknowledge the polls' legitimacy and reiterated its position that the peninsula "remains an integral part of Ukraine."
