WASHINGTON — The Obama administration on Tuesday imposed financial restrictions on 34 additional people and entities for helping Russian and Ukrainian companies evade US penalties and other infractions, prompting threats of retaliation from the Kremlin.

The action helps ‘‘maintain the efficacy of existing sanctions’’ established after Russia’s annexation of the Crimean peninsula last year and support for eastern Ukrainian separatists, the Treasury Department said.

Fourteen are linked to ‘‘serious and sustained evasion’’ or are subsidiaries of already sanctioned firms. The department called six separatists and two former Ukrainian government officials ‘‘complicit’’ in corruption or in destabilizing Ukraine. Twelve were targeted for operating from Crimea. Americans can no longer do business with those listed, and any US assets they have are now frozen.

John Smith, the department’s acting sanctions boss, demanded that Russia adhere to a February cease-fire in Ukraine. That agreement compelled Moscow to withdraw forces and materiel from eastern Ukraine’s front lines, release prisoners, allow the Western-backed government in Kiev to reassume control over its borders and provide unfettered access to international monitors.

Russia quickly decried the announcement.

‘‘This is a continuation of the unfriendly line against Russia that runs counter to logic,’’ Kremlin spokesman Dmitry Peskov said. His government would review the US decisions ‘‘and then gather proposals on possible countermeasures,’’ he said.

The US has been trying to find the right balance of carrots and sticks to push Russia into making a full withdrawal from eastern Ukraine, while securing its cooperation on ending Syria’s civil war, enforcing this summer’s Iran nuclear agreement and advancing other international priorities.