PM Theresa May had said the Salisbury poisoning was "part of a pattern of Russian aggression against Europe".
Moscow denies responsibility for the attack on an ex-spy and his daughter.
The EU said its ambassador to Russia was recalled "for consultations".
Former Russian spy Sergei Skripal and his daughter Yulia remain in a criticalbut stable condition after the attack on 4 March.
The European Council statement added: "We stand in unqualified solidarity with the United Kingdom in the face of this grave challenge to our shared security."
Mrs May briefed her counterparts on Thursday on the poisoning of the Skripals, who remain in a critical but stable condition in hospital after they were found unconscious on a bench.
Detective Sergeant Nick Bailey, who became ill after responding to the incident, is no longer in a serious condition and has been discharged from hospital.
The prime minister set out the evidence the UK has against Russia - including the positive identification of the chemical used as a type of Novichok nerve agent and the knowledge that Russia has produced this agent within the last 10 years.
BBC
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