Officials in Ukraine said a drone attack on a residential complex in the northern city of Kharkiv killed at least seven people, including a 1-year-old girl.
Strikes also hit the southeastern city of Zaporizhzhia, killing three people, they said.
"This was a demonstrative and cynical Russian strike," Zelenskiy wrote on X.
"The Russian war machine continues to destroy lives despite everything. Putin will commit demonstrative killings to maintain pressure on Ukraine and Europe, as well as to humiliate diplomatic efforts."
After rolling out the red carpet for Russian President Vladimir Putin at a summit in Alaska on Friday, Trump is leaning on Ukraine to accept a peace deal to end Europe's deadliest war in 80 years.
The war has killed or wounded more than a million people from both sides, including thousands of mostly Ukrainian civilians, according to analysts.
Kyiv and its allies worry that Trump could force an agreement more favourable to Moscow.
The Russian defence ministry's daily report said its forces had attacked Ukrainian units in the Kharkiv region but did not refer to any strike on the city of Kharkiv.
Russia says it does not deliberately target civilians.
On Monday, Trump will meet Zelenskiy first and then the leaders of Britain, Germany, France, Italy, Finland, the European Union and NATO, the White House said.
The European leaders are flying to Washington to show solidarity with Ukraine and to press for strong security guarantees in any post-war settlement.
Trump's team stressed on Sunday that there had to be compromises on both sides.
But Trump put the burden on Zelenskiy to end the war that Russia began with its full-scale invasion in February 2022.
Ahead of the meeting, he said in a social media post that Ukraine should give up hopes of getting back Crimea, annexed by Russia in 2014, or of joining the NATO military alliance.
Zelenskiy "can end the war with Russia almost immediately, if he wants to, or he can continue to fight," Trump said on Truth Social.
Trump will meet Zelenskiy at 1:15pm local time (03:15am Tuesday AEST) in the Oval Office and then with all the European leaders in the East Room, the White House said.
The Ukrainian president, seeking to avoid a repeat of the heated Oval Office meeting he had with Trump in February, said after arriving in Washington late on Sunday, he was grateful to the president for the invitation.
Ukraine and its allies have taken heart from some developments, including Trump's apparent willingness to provide post-settlement security guarantees for Ukraine.
A German government spokesperson said on Monday that European leaders would seek more details on that in the talks in Washington.
Zelenskiy has already all but rejected the outline of Putin's proposals from the Alaska meeting, including for Ukraine to give up the rest of its eastern Donetsk region, of which it currently controls a quarter.
Zelenskiy is also seeking an immediate ceasefire to conduct deeper peace talks.
Trump previously backed that but reversed course after the summit with Putin and indicated support for Russia's favoured approach of negotiating a comprehensive deal while fighting rumbles on.
Russia launched missiles and drones in overnight attacks that included strikes on Kharkiv.
"They hit an ordinary apartment block, many flats, many families were living here, small children, children's playground, residential compound, there are no offices here or anything else, we lived here peacefully in our homes," said Olena Yakusheva, a resident.
