In an interview with the Press & Journal, Mr Johnson said he was “sorry if people take offence at distorted quotations from old newspaper articles”.
The Scotsman revealed how Mr Johnson had written in a 2005 article for the Spectator magazine, which he edited, that “government by a Scot is just not conceivable in the current constitutional context”.
“Of course I am sorry if people take offence at distorted quotations from old newspaper articles – but one of the things I want to make clear is that Conservatives must reach out beyond the Westminster bubble and that means not just speaking in waffle and jargon,” he said.
“I am the only candidate who can truly unite the Conservative Party, deliver Brexit and keep the Jeremy Corbyn out of Number 10.”
Ahead of this evening's hustings event in Perth, SNP deputy leader Keith Brown challenged Mr Johnson and his rival, Jeremy Hunt, over their rejection of further devolution and a second Scottish independence referendum.
“They are both rabid Brexiteers who would happily ignore the fact that Scotland voted to remain in Europe, and hammer our economy by dragging us off the Brexit cliff edge. And they’ve voted together to inflict misery on families with relentless austerity and punishing welfare cuts.
“If either of them want to show some respect to the people of Scotland they’ve got some big questions to answer."