Zelenskiy had floated the cessation, starting on May 6, in response to Russian leader Vladimir Putin's own proposed ceasefire from May 8 to 9 to coincide with its World War II victory commemorations.
In a statement, Zelenskiy said Russia - which did not confirm its adherence to Ukraine's proposal - had committed 1,820 violations by late morning on Wednesday.
"Russia's choice is an obvious spurning of a ceasefire and of saving lives," he said.
Speaking later in his nightly video address, Zelenskiy said Russia "has responded to the proposal only with new strikes and new attacks" and Ukraine would determine "our entirely justified responses".
He said Ukraine was ready to work for peace but that "if the one person in Moscow who cannot live without war is interested only in a parade and nothing else, that is another matter".
"Russia has fought to the point where even their main parade now depends on us."
Russia, citing an increased threat of Ukrainian attacks, says it will hold a slimmed-down version of its annual Victory Day parade in Moscow this week without military hardware.
In Moscow, Foreign Ministry spokeswoman Maria Zakharova said Russia had warned diplomatic missions to evacuate staff promptly from Kyiv in the event of a mass strike by Moscow in response to any attempt by Ukraine to disrupt Victory Day commemorations.
Zakharova, in a video posted on Telegram, said her ministry "strongly urges the authorities of your country...to treat this statement with the utmost responsibility".
On Monday, Russia's defence ministry had warned that it would respond to Ukrainian attacks during victory celebrations with a "massive missile attack" on the Ukrainian capital Kyiv.
Moscow Mayor Sergei Sobyanin said on Monday that a Ukrainian drone had struck a building in Russia's capital overnight, but had caused no casualties.
Officials in the northeastern region of Sumy said two people were killed in separate Russian drone attacks on a civilian car and a kindergarten where children were not present.
In major cities such as Kharkiv, Kryvyi Rih and Zaporizhzhia - where an attack on Tuesday killed 12 people - private buildings, infrastructure and industrial sites were damaged in air attacks after midnight, officials said.
"This shows that Russia rejects peace and its fake calls for a ceasefire on May 9th have nothing to do with diplomacy," said Ukrainian Foreign Minister Andrii Sybiha on X.
"Putin only cares about military parades, not human lives."
The rival overtures come amid stalled US-backed peace talks to end the more than four-year war, and as Russia presses an offensive to capture the rest of Ukraine's eastern Donetsk region.
In his remarks, Zelenskiy also said, citing Ukrainian intelligence, that Russia was concentrating its air defences around Moscow, a fact which "creates additional opportunities" for long-range attacks by Ukraine elsewhere.
Kyiv's forces have stepped up attacks in recent months on military-industrial and energy sites across Russia, particularly oil infrastructure, in a bid to weaken the Kremlin's war machine.
