Russia is threatening the European Union with countermeasures in case of new sanctions.
"We will not leave such attacks ... unanswered," Foreign Minister Sergei Lavrov said on Thursday during a visit to Armenia, according to the Interfax agency.
The background to the comment is entry bans imposed by Russia on eight senior EU politicians and other officials last Friday in response to earlier EU sanctions.
In response, European Union leaders threatened to take "appropriate measures."
Among those affected by Russia's latest sanctions are EU Parliament President David Sassoli and Commission Vice-President Vera Jourova.
The Foreign Ministry in Moscow had justified the entry bans with the EU sanctions against Russian officials in connection with the case of the poisoned and imprisoned dissident Alexei Navalny, which it considered unfounded.
Because of the poison attack on Navalny that nearly killed him and required months of medical attention in Berlin's Charite Hospital, the EU had already imposed entry and asset bans on people suspected to be responsible from circles close to Russian President Vladimir Putin.