Russian Foreign Minister Sergei Lavrov on Monday accused Kiev of "dangerous" moves in the Kerch Strait after a confrontation between Russian and Ukrainian navy ships.
Lavrov said Ukraine had violated international norms with "dangerous methods that created threats and risks for the normal movement of ships in the area".
On Sunday, Russia boarded and seized three Ukrainian ships in the strait off Moscow-annexed Crimea, accusing them of illegally entering Russian waters in the Sea of Azov.
Ukraine has demanded the release of its sailors and more sanctions against Moscow.
Lavrov called the incident a "clear provocation" by Kiev and accused the European Union of "blind support" for Ukraine.
"We call on Kiev's Western sponsors to calm those who are trying to earn political points on military hysteria," he said, implying the incident was planned ahead of Ukraine's presidential election next year.
The confrontation at sea has raised fears of a wider military escalation and the UN Security Council was to hold an emergency session later Monday to consider a response.