Prime Minister Boris Johnson has called for a "step-by-step" move away from dependence on Russian oil and gas as a result of the Ukraine war.
After talks with the Canadian and Dutch PMs, Mr Johnson said nations have to work together to secure alternatives.
Canada's PM Justin Trudeau said Europe did not want to repeat its mistake of being too dependent on Russia.
But Dutch Prime Minister Mark Rutte warned forcing a boycott now would have "enormous consequences".
And in Germany, Chancellor Olaf Scholz cautioned against banning Russian oil and gas.
In a statement, he said Europe had "deliberately exempted" Russian energy from sanctions because its supply cannot be secured "any other way" at the moment.
Mr Johnson's call came at a Downing Street news conference after he, Mr Trudeau, and Mr Rutte discussed new sanctions against Russia and aid for Ukraine.
Asked about claims that the US was in active discussions with European nations about banning imports of Russian oil, Mr Johnson said Western allies are "moving very, very fast" - and things which weeks ago would not have been considered are "now very much on the table".