"Coming from Uncle Sam, it is a piece of outrageous and exorbitant hypocrisy," Johnson, a leading member of the campaign for Britain to leave the EU, wrote in his regular column for the Daily Telegraph.
"Can you imagine the Americans submitting their democracy to the kind of regime that we have in the EU?" he asked, adding: "This is a nation born from its glorious refusal to accept overseas control."
"In urging us to embed ourselves more deeply in the EU's federalising structures, the Americans are urging us down a course they would never dream of going themselves," he wrote.
"That is because they are a nation conceived in liberty. They sometimes seem to forget that we are quite fond of liberty, too."
The Independent newspaper yesterday reported that Obama, who has already expressed support for Britain's EU membership, was expected to come to London at the end of April.
A spokeswoman for Prime Minister David Cameron's Downing Street office today declined to comment on the report.
"Other people will set out their views, the choice for the British people is whether or not they listen to them but then they get to make up their own minds," she said.
Obama is heading to Germany in late April to talk trade with Chancellor Angela Merkel and promote US exports at the Hannover industrial technology fair, which takes place April 25-29.
Cameron favours keeping Britain in the EU, following a renegotiation of the country's relations with Brussels.
Opinion polls indicate that the race is finely balanced, with those who want to remain at 51 per cent and those in favour of leaving at 49 per cent, according to a survey of polls by the What UK Thinks research project that excludes undecided voters.
Up to 20 per cent of voters have said they have not yet made up their minds which way to vote.
