Morgenshtern said in an interview that he "doesn't understand" why Russia still celebrates its victory over Nazi Germany in 1945.
A popular Russian rapper is under investigation after allegations that he insulted Russia's World War II history.
Alisher Morgenshtern drew anger from Russian war veterans for comments about the country's Victory Day celebrations.
In an interview on YouTube, Morgenshtern stated that he "doesn't understand" why Russia still celebrates the Soviet Union victory over Nazi Germany.
The 23-year-old rapper also questioned the amount of money that had been spent on the May 9 commemoration event.
"I honestly don’t understand this celebration of a victory that happened 76 years ago," Morgenshtern said. "Every year we spend millions on it."
The video interview was uploaded to YouTube on Monday and has since received more than 3 million views.
His comments soon sparked backlash and an organisation of Russian war veterans filed a complaint with the country's Investigative Committee.
The group said Morgenshtern's remarks had "insulted the historical memory" of those who fought and died in World War II.
The Committee said in a statement that they would investigate whether Morgenshtern's comments had violated any Russian law.
The Victory Day celebrations on 9 May feature military parades in major cities across Russia, in memory of the 20 million people who died during World War II.
Since coming to power, President Vladimir Putin has emphasised Russia's role during the war and has accused Western opponents of downplaying Russian history.
Speaking to reporters on Tuesday, Kremlin spokesman Dmitry Peskov said that Morgenshtern was likely speaking "not out of malice but out of ignorance".
But Peskov added that the rapper should take "moral responsibility" for his statements.
If found guilty of public insult and the "rehabilitation of Nazism", the rapper could face a maximum sentence of three years in prison.
In a statement on Instagram, Morgenshtern apologised to Russian war veterans and said his comments had been "taken out of context".
"I respect and am proud of our veterans, but unfortunately I can't get my thoughts right," the rapper said, accusing the media of "distorting" his words.
"I in no way meant to belittle the importance of this event," he said, adding that he had also said in the interview that Russian veterans should be given greater subsidies.
The rapper has previously been fined 100,000 rubles (€1,225) for promoting drug use in some of his music videos.