He spoke at the Abu Dhabi Ideas Weekend, held to share ideas on global challenges, in a session on the “polarisation” of society which some see as the cause of Britain’s Brexit vote and America’s election of President Donald Trump.
Mr Cameron campaigned for the Remain side in Britain’s 2016 referendum and quit Downing Street the day after the vote for Brexit, despite having said he would see out his term whatever the result.
Today he suggested the shock of the 2008 world financial crisis and concerns about immigration had brought about the Brexit vote.
“There was genuine concern about international organisations that needed to be addressed,” he said, a local newspaper in the Gulf state reported.
“That’s what we did.”
The situation had been “unsustainable”, making a referendum inevitable.
There had also been demands to “do better” at controlling immigration.
Mr Cameron said the goal now must be to maintain close economic ties with Europe, “the biggest single market in the world”.
He commented: “We were always unhappy tenants. Now we have to be happy and contented neighbours.”
The session also included his former campaign chief Sir Lynton Crosby, the Australian-born political strategist who was knighted in 2016 after helping the Tories to victory in the 2015 general election.
Former French President Nicolas Sarkozy was another of the speakers at the Abu Dhabi conference.
In January Mr Cameron was caught on camera at the Davos World Economic Forum telling billionaire steel tycoon Lakshmi Mittal that Brexit was “a mistake, not a disaster. It’s turned out less badly than we first thought”.