"Undoubtedly, the Ukrainian side's decision seriously devalues the forthcoming contest. It probably strikes a blow the prestige of Eurovision," Peskov told reporters.
He expressed hope that Kiev would reconsider the three-year ban handed down to Samilova on Wednesday ahead of the contest.
"We know that the Eurovision representatives have expressed their regrets in connection with this decision," Peskov said.
On Wednesday, the Security Service of Ukraine (SBU) banned entry to the country for three years for Samoilova, citing the alleged "violation by her of the Ukrainian legislation." The Russian singer visited Crimea in 2015 with a concert without obtaining a permit from the Ukrainian authorities. In accordance with the country's law, Ukraine may ban entry for foreigners who had visited post-referendum Crimea without a permit from Kiev.
The European Broadcasting Union (EBU) has issued a statement saying that it is working on ensuring that all participants could take part in the upcoming competition.