The White House's decision has further raised fears that Ukraine could be left exposed to Moscow's escalating assaults with winter approaching.
Zelenskiy described Trump's move to put sanctions on hold as unfortunate, but did not directly criticise the US leader despite deepening tensions between Ukraine and Washington in recent days.
"A decision was unfortunately made in America to completely disregard the Lindsey Graham Act, which was supposed to impose truly effective pressure on Russia to bring this war to an end," Zelenskiy wrote on social media on Saturday.
He also expressed hope that the new sanctions could be revived.
"This act could have helped enormously - and still can! But it needs to actually work, and every voice in support of it matters," he said.
Zelenskiy said Moscow had carried out a massive strike on Ukraine's energy infrastructure, targeting more than 15 sites across the country.
"The sheer scale and unrelenting pace of Russia's strikes, specifically against our energy sector, are unfortunately having severe consequences," he said.
Ukraine's air force said that Russian forces launched four cruise missiles and 332 attack drones overnight.
All of the missiles and 289 of the drones had been suppressed or destroyed, it said.
Russia's heavy bombardment of the power grid before winter has been an annual feature of the war, aimed at wearing down Ukraine's appetite for the fight by denying civilians heat and running water.
Ukrainian officials have warned that Russia is stockpiling ballistic missiles for more attacks in the coming months.
