In a speech to the Scottish Conservatives virtual conference on Sunday, the Prime Minister also launched an attack on Scottish Labour, labelling them “too weak” to be trusted to take on the SNP and stop Indyref2.
Mr Johnson also highlighted the successes of the UK Government’s handling of the coronavirus pandemic including the delivery of personal protective equipment (PPE), testing and the vaccination programme, describing it as demonstrating “the United Kingdom’s collective strength”.
The speech comes as support for the Union rises in Scotland, bucking a trend during the Covid-19 pandemic of a lead for Scottish independence.
Mr Johnson’s speech also follows the decision by the UK Government to move hundreds of civil service jobs to Glasgow as part of a Cabinet Office relocation and reports of plans for the House of Commons to sit in Edinburgh for two weeks each year amid a charm offensive to bolster support for the Union.
The Prime Minister said: “I just find it incredible then that the SNP would choose this moment to again push their campaign for separation.
“Just when everything is beginning to reopen again, when we will soon be reunited with our friends and family, the SNP think that this is the time to turn us all against one another, to start another political fight.
“Perhaps I shouldn’t be surprised – it is their party’s obsession. Yet surely even they have a sense of priority, of what is important right now.
“The SNP can see – after the impact of coronavirus – that people want time to renew their lives and to rebuild relationships that have become stretched. They know that workers are concerned primarily about their jobs and businesses concerned for their future.
“How can the SNP say that a referendum is the priority to them? It is the last thing they need right now.
“It is clear, though, that the SNP are not listening. They are intent on pushing for a referendum, regardless of the cost to Scotland and the whole of the UK.”
Mr Johnson said that for indyref2 to be stopped, voters must back the Scottish Conservatives and not other unionist parties such as Scottish Labour.
He said: “Labour are too weak and they cannot be trusted to stand up to the SNP.
“They would rather work with the SNP to be seen as anti-Conservative than stand up for the unity of the United Kingdom.
“We cannot put the future of our country in Labour’s hands, not in Edinburgh or in London.
“So, it is up to the Scottish Conservatives to again stop the SNP from winning a majority in May just like they did in 2016. The only party that can cut the SNP down to size.”
Finishing his speech, Mr Johnson added: “The SNP want to divide us, to turn Scotland against itself, at this of all times.
"So that is the goal for all of you in May and what is at stake – to stop an SNP majority government and secure Scotland’s and the whole of the UK’s economic recovery from the coronavirus pandemic.”
Reacting, Scottish Labour leader Anas Sarwar said: “Boris Johnson’s Conservatives want to take us back to the old divisive arguments.
“They want us to argue with each other rather than focus on the priorities of the Scottish people – creating jobs, a comeback plan for education and rebuilding our NHS.
“Only Scottish Labour is going into this election with a focus on national recovery and uniting our country.”
Before Mr Johnson had given his speech, the SNP’s Michael Russell challenged the Prime Minister to make it clear whether he believes Scotland has the right to choose independence in another independence referendum.
He said: “No one is proposing holding an independence referendum now, but if the people back a post-pandemic referendum in the coming election then democracy must prevail.
“So today I’m challenging Boris Johnson to make his position crystal clear: does he accept that Scotland has the democratic right to choose independence in a post-pandemic referendum – or is his position that the people should never be allowed to choose their own future under any circumstances?
“In true Trump-like fashion, Boris Johnson will address Tory party members today and signal that should they lose the Holyrood election in May – then he simply won’t recognise the result.
“But privately, the Prime Minister and his colleagues know that a Trump-like bid to deny democracy is untenable and unacceptable – which is why they are so busy in the background making plans on how to contest an independence referendum.
“If Scottish voters in May back the SNP’s plan to hold a post-pandemic referendum, then he has no right to block it."