The British-Iranian charity worker is currently refusing to eat food in prison in protest at her “unfair imprisonment” – and her husband has vowed to fast outside the Iranian embassy in London until her hunger strike ends in an act of solidarity.
Speaking on the second day of his hunger strike , Mr Ratcliffe criticised Tory leadership frontrunner Mr Johnson’s previous comments about the case.
“He clearly made a mistake and clearly tried to correct it and made a promise that he wasn’t able to deliver on," he told the Andrew Marr Show. “At times I’ve resented him for it and there are bits I did resent him for.”
Mr Johnson said in 2017 that Ms Zaghari-Ratcliffe was working in Tehran training journalists, comments used by Iran to allege she was engaged in “propaganda against the regime”.
The family will now “push” foreign secretary Jeremy Hunt for his wife’s release, Mr Ratcliffe said.
Mr Johnson's fellow Tory leadership contender has urged Iran to release Ms Zaghari-Ratcliffe and not “drag her into” its disagreements with Britain.
The couple decided to start the hunger strike following the fifth birthday of their daughter, Gabriella, who has not been allowed to leave Iran since her arrest in 2016.
It came after Ms Zaghari-Ratcliffe refused food for three days in January in protest against being denied access to medical care.
Mr Ratcliffe said he wife had "been on hunger strike before."
He added: "It achieved something, but not much. I said that if she did it again I would stand in solidarity with her. A hunger strike in prison, nobody gets to see it, a hunger strike here is much more public.”
Ms Zaghari-Ratcliffe was arrested in April 2016 at Imam Khomeini Airport in Tehran as she prepared to board a plane with Gabriella back to the UK after visiting relatives.
The 40-year-old is serving a five-year sentence in the notorious Evin Prison.
Mr Hunt granted Ms Zaghari-Ratcliffe diplomatic protection in March but Tehran refuses to acknowledge her dual nationality.
Additional reporting by PA