The UK government has insisted it does not want its diplomatic dispute with Russia to go "any wider".
Mr Litvinenko died in a London hospital in November 2006
Four Russian embassy staff have been expelled over Moscow's refusal to hand over the chief suspect for the murder Alexander Litvinenko in London.
But Europe minister Jim Murphy said the expulsions had been made with "deep, deep regret" and insisted it was not acting in a "macho" way.
Moscow has promised an "appropriate and targeted" response.
The European Union's Portuguese presidency expressed its "disappointment" that Russia had not dealt "constructively" with the UK over the Litvinenko case.
Facing questions from the Commons foreign affairs committee, Mr Murphy said the expulsions of Russian diplomats been a "targeted, specific measure" intended to secure the extradition of the chief suspect - former KGB agent Andrei Lugovoy.
He added: "It was a decision taken with deep, deep regret. We have no ambitions towards a macho response.
"We have taken a considered, measured response which we think is appropriate in these circumstances.
"Our intention is to contain process. We have no ambition to go wider."
In a statement, the EU's Portuguese presidency said: "The EU expresses its disappointment at Russia's failure to cooperate constructively with the UK authorities.
"The EU underlines the importance of urgent and constructive cooperation by the Russian Federation on this matter."
Russia's deputy foreign minister Alexander Grushko has said the expulsions will complicate "vitally important" security issues.
The Foreign Office said it had set out its position adding: "No retaliation on Russia's behalf is justified."
A full statement is expected from Moscow, which has warned Britain to expect "serious consequences".
KEY EVENTS IN CASE
1 November 2006: Alexander Litvinenko meets Andrei Lugovoi and another Russian at a London hotel
23 November 2006: Litvinenko dies in a London hospital
24 November 2006: A Litvinenko statement accuses Russian President Vladimir Putin of involvement in his death. Experts say Litvinenko was poisoned
6 December 2006: UK police say they are treating the death as murder
22 May 2007: Lugovoi should be charged with Litvinenko's murder, British prosecutors say
28 May 2007: UK makes formal request for Lugovoi's extradition from Russia
Mr Lugovoi, who is accused of murdering Mr Litvinenko in London last year, denies involvement.
Mr Litvinenko, who had taken UK citizenship, died of exposure to radioactive polonium-210 in London in November last year.
The radioactive isotope used to poison him was found in several places that Mr Lugovoi had visited in London.
But Mr Lugovoi told Russian television that the outcome of the inquiry had been predetermined.
Under the European Convention on Extradition 1957, Russia has the right to refuse the extradition of a citizen.
The UK has the right to request Mr Lugovoi be tried in Russia, but the UK's director of public prosecutions, Sir Ken Macdonald, has already turned down the offer.
The UK's director of public prosecutions has recommended Mr Lugovoi be tried for murder by "deliberate poisoning".