"Any attempts to put pressure on Russia are simply pointless," Dmitriev said, adding that some forces were trying to disrupt the dialogue between Moscow and Washington.
Medvedev wrote that pressure from Congress to sanction Russian companies "still doesn’t change the most important thing: these decisions are an act of war against Russia."
A Russian drone strike hit a synagogue and residential buildings in Kyiv’s Podil district, reportedly wounding four people and causing major roof damage.
Trump had announced last week that he and Putin would meet soon in Hungary to try to bring an end to the war in Ukraine. But Putin has been unwilling to consider concessions.
European leaders called on Washington on Tuesday to hold firm in demanding an immediate ceasefire in Ukraine, with present battle lines to serve as the basis for any future talks.
A subsequent daytime attack by about 20 Russian kamikaze drones killed four civilians and wounded at least seven more in the town of Novhorod-Siverskyi, local officials said.
After his meeting with Zelensky, Trump publicly called for a ceasefire on the current frontlines, a position that the Ukrainian president then embraced in comments to reporters.
Zelensky later accused Russia of taking advantage of the ceasefire deal in Israel to launch more vicious attacks on Ukraine.
This comes after Ukrainian President Volodymyr Zelensky said that he would not use the missiles to target Russian civilians in comments to Fox.
The first lady said Putin had responded to her letter earlier this year and that there remains an open line of communication.
This comes as over one million houses in Ukraine were left without power due to a Russian strike on Ukrainian energy facilities.