"We will find every murderer," the president said in his daily video address on Sunday after at least 16 people were killed and 64 wounded in Russian attacks in Kherson on Saturday.
Zelenskyy warned Ukrainians of more Russia attacks in the last days of the year.
"We must be aware that our enemy will try to make this time dark and difficult for us," he said, adding "we must be prepared for any scenario."
The Ukrainian president said Moscow was trying to compensate its losses "with the cunning of its propagandists."
Meanwhile, the Ukrainian military said on Sunday that a meeting in the village of Zabaryne was targeted by Kyiv's forces, injuring at least 70 Russian officers. The number of fatalities was unknown.
