The EU's ambassador to Russia labelled the war against Ukraine unprovoked and illegal in a speech near the Kremlin in Moscow on Thursday as anti-Western activists protested nearby.
Roland Galharague was speaking at a belated event to mark Europe Day, which is celebrated on May 9.
"The wars of today only fuel the hatred of tomorrow," the Frenchman said at a ceremony involving diplomats from dozens of countries.
A leaflet distributed by the anti-Western protesters stated that it was absurd to celebrate Europe Day in the centre of Moscow while Russian blood was being shed through the delivery of Western weapons to the "criminal regime in Ukraine."
The European Union is making policy against Russia and celebrating this in Moscow, the demonstrators said.
"Russian blood is on your hands" was written on one red banner.
Diplomats reported that they had been approached by activists and Russian media at the entrance to the hotel where the celebration was taking place.
In contrast, Russian human rights activist Svetlana Gannushkina from the Nobel Peace Prize-winning organization Memorial said that Russian blood was being shed by Moscow's war against Ukraine.
In comments to dpa, she praised the fact that Galharague had bravely condemned the war against Ukraine at an event in the centre of Moscow.
"That is appropriate and right," she said.
In his speech, the EU diplomat also emphasized that the EU wanted to maintain contact with ordinary citizens of Russia and that this is why embassies and consulates continue to stay open in Moscow.