The Conservative former prime minister said Johnson privately claimed there could be a "fresh renegotiation, followed by a second referendum" - which he now says he opposes.
"It's going to take a lot of work between now and October 17" when European Union leaders gather for their final summit before Britain's scheduled exit from the bloc, he told the Mail on Sunday newspaper.
The prime minister, who faces an October 31 deadline to withdraw from the European Union or seek a delay if he can't reach a deal, said the United Kingdom will break out of its "manacles" the way Bruce Banner did when he turned into his enormous green alter ego.
Cameron said that as prime minister, he felt he could not hit back as hard, resulting in "asymmetric warfare".
'Hulk always escaped, no matter how tightly bound in he seemed to be - and that is the case for this country, ' the Prime Minister told the Tory supporting paper.
More than three years later, nobody knows how the Brexit saga will end, with Prime Minister Boris Johnson remaining convinced that a deal with Brussels will be struck by the October 31 deadline when Britain is scheduled to leave the bloc, despite a multitude of hurdles to navigate.
The Brexit Secretary and Michel Barnier, the EU's chief negotiator, will join the talks in Luxembourg in the hope of hammering out a deal.
Johnson´s strategy faces opposition at home, where rebel and opposition MPs have passed a law aimed at forcing him to seek a Brexit delay.
"When I got this job everybody was saying there can be absolutely no change to the Withdrawal Agreement, the backstop was immutable, the arrangements by which the United Kingdom was kept locked in to the European Union forever, they said no-one could change that".
In the interview, Johnson said if negotiations break down with Brussels, he will ignore last week's House of Commons vote ordering him to delay Britain's departure from the bloc until January 31, 2020.
He also accused Mr Johnson of not believing in Brexit and said he only backed it to further his career.
Opinion polls late on Saturday painted a conflicting picture of the Conservative Party's political fortunes under Johnson, who wants to hold an early election to regain a working majority in parliament.
Talks are still stalled on the contentious issue of the Irish border backstop, a policy meant to ensure there are no checks on goods crossing the U.K.'s land border with Ireland.
Away from politics and into the courts, and Tuesday sees the Supreme Court hearing appeals about whether the decision to suspend Parliament was legal after a Scottish court said it was unlawful.
Mr. Johnson has insisted that he wants a deal but he has refused to consider any delay, further antagonizing MPs including many fellow Conservatives.
And, in an update to the European Parliament last week, Mr Barnier said that while "the United Kingdom has shown a desire to intensify contacts. we will see in the coming weeks if the United Kingdom are able to give us concrete proposals in writing, which are legally operable".
"A huge amount of progress is being made", he said, referring to "technical talks" on border procedures between his Brexit adviser David Frost and Barnier´s team.
The 52-year-old Cameron attacked former allies Johnson and Michael Gove, who helped spearhead the "Leave" campaign. Chuckling, the minister told Sky News: 'I'd rather be backing a character and a leader who's the Hulk rather than one who is on the "chicken run" as Jeremy Corbyn is'.