Ukrainian presidential adviser Oleksiy Arestovych has offered his resignation after suggesting a Russian missile which hit a building in Dnipro, killing 44 people, was shot down by Kyiv.
Mr Arestovych apologised and said he had made a "fundamental error".
The original remark caused widespread anger in the country, and was used by Russian officials to blame Ukraine.
The adviser is a well-known figure because of his daily updates on YouTube, watched by millions.
Ukraine's President Volodymyr Zelensky has not yet commented on Mr Arestovych's decision to resign.
Hours after Saturday's missile strike hit an apartment building in Dnipro, Mr Arestovych initially said it appeared that the Russian missile had fallen on the building after it was shot down by Ukrainian air defences.
Ukraine said the building was hit by a Russian Kh-22 missile, which it does not have the capability to shoot down and is reportedly extremely inaccurate.
Ukrainians reacted angrily to Mr Arestovych's initial comments, with some accusing him of strengthening the position of Russian propagandists. Some Ukrainian parliamentarians signed a petition calling for Mr Arestovych to be dismissed as a government official.
He later posted a letter tending his resignation and said he had made a "fundamental error".
"I offer my sincere apologies to the victims and their relatives, the residents of Dnipro and everyone who was deeply hurt by my prematurely erroneous version of the reason for the Russian missile striking a residential building," he wrote in a longer post on Telegram.
Mr Arestovych is one of the most public Ukrainian faces of the war, using his YouTube channel to hold daily discussions on issues related to the conflict. The channel has more than 1.6 million subscribers, and his videos often have more than 200,000 views. Unusually for Ukrainian officials, he speaks in Russian rather than Ukrainian.
Before his resignation offer, his comments had been used by Russian officials to blame Kyiv for the strike.
Kremlin spokesman Dmitry Peskov said Russian attacks "do not strike residential buildings" and suggested it was caused by Ukrainian air defences, a conclusion he said had also been reached by "some representatives of the Ukrainian side".
Ukrainian officials have so far said that at least 44 people died in Saturday's strikes with several others missing, and that there is "minimal" chance of finding others alive.
Kyiv, Kharkiv and Odesa were also hit on Saturday in attacks which Moscow said were targeted at Ukraine's military and energy infrastructure.
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