"If the Kyiv regime is consciously committing such inhumane... acts of terror against civilians, against children, then this is an entirely different paradigm," the Kremlin spokesman said.
Russian news agencies quoted a statement by diplomats at Russia's mission to the European Union as saying the measures were meaningless without a decision from the UN Security Council.
Zelensky said Ukraine was able to secure US weaponry through the PURL program under which NATO countries can finance the purchase of weapons for Kyiv.
Ukraine has proposed Turkey as a neutral venue for Zelenskiy-Putin peace talks, aiming to restart negotiations and avoid meeting in Belarus or Russia.
A shooting in Kyiv's Holosiivskyi district left six dead, including a hostage, after a Russian-born man opened fire on passersby before barricading himself in a supermarket, where police killed him.
A Ukrainian soldier said Russian reconnaissance drones were still circling the area despite the ceasefire, while the Belgorod region's governor said two people were killed by Ukrainian shelling.
Putin's announcement was similar to a 30-hour ceasefire he ordered last year. Each side accused the other of violating it.
There were no reports of injuries or damage to the power station, Estonian authorities said.
Izvestia said the Kremlin had confirmed the pause. Zelensky said that it was time to resume peace talks and that Ukrainian negotiators would travel to the US on Saturday.
Exiled teacher Pavel Talankin’s "Mr. Nobody Against Putin" won a BAFTA for exposing the militarization of Russian schools. The film uses secret footage to show child indoctrination.
Ukrainian President Volodymyr Zelensky said Russia had launched 420 drones and 39 missiles in another night of attacks on energy and other critical infrastructure.
