Speaking to the Foreign Affairs Select Committee, he said: "Nazanin Zaghari-Ratcliffe, nor her family, has been informed about what crime she has actually committed".
The 38-year-old dual-national charity worker was accused of plotting to topple the regime, which she denies, and was later sentenced to five years in prison.
Mr Johnson returned from Brussels to answer an urgent question on the case in the House of Commons, amid continuing concern that his suggestion to a parliamentary committee that Mrs Zaghari-Ratcliffe was training journalists in Iran has exposed her to the threat of the doubling of her five-year jail sentence.
PA Wire PA Images Boris Johnson plans to visit Iran later this year
He also wants the Foreign Secretary to take him to Iran so he can see his wife and daughter Gabriella for the first time in 18 months.
Mr Ratcliffe is expected to raise the continued coverage of Mr Johnson's comments in the Iranian media and will seek to clarify the position on any new charges she faces.
The woman's employers and family have always denied this.
It follows an apology by the foreign secretary for "anguish" caused by false remarks he made about the reason for her travels.More news: Airbus seals record 430-jet deal to outshine Boeing in Dubai
Mr Johnson said: "Yes, of course, I apologise for the distress, the suffering that has been caused by the impression that I gave that the Government believed, that I believed, she was there in a professional capacity". She has been confined in a high-security Iranian jail ever since while her daughter, now three, remains at the Tehran home of Nazanin's parents.
There have been calls for Johnson to quit in the wake of the gaffe, but Ratcliffe said he should stay and clean up his mess.
This led United Nations human rights experts to express "grave" concerns for her welfare, calling on the Iranian authorities to release her at once.
Consular officials will be at the meeting, along with Middle East minister Alistair Burt, who has already met Mr Ratcliffe and visited Mrs Zaghari-Ratcliffe's family in Tehran.More news: Barcelona close to agreeing terms with Man United target
Ratcliffe will meet Johnson and his consular specialists at the Foreign Office on Wednesday.
He will speak to the Foreign Secretary at the Foreign Office at 10am, in a bid to help secure his wife's release from Iran.
The family's local MP Tulip Siddiq told Sky News that Mrs Zaghari-Ratcliffe had sobbed inconsolably during an earlier phone call with her husband, saying: 'She just said that she couldn't believe that Boris Johnson would make those comments.More news: Brad Paisley schedules Save Mart Center concert
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