The 68-year-old husband and father, a retired civil engineer, was arrested in August 2017 while visiting his elderly mother in Tehran.
He did not return to the UK until last week when he touched down at Brize Norton on the same plane as charity worker Nazanin Zaghari-Ratcliffe.
Mr Ashoori said he is unsure whether he will meet the prime minister who he said did not even spare five minutes to call his family while he was jailed in Iran.
Appearing on Sky News’ Beth Rigby Interviews, Mr Ashoori said his wife, Sherry Izadi, did not get a response from Mr Johnson when she contacted him about her husband’s case.
He also told the broadcaster about a voice message he himself sent Mr Johnson, explaining: “That was during the time of the Covid that I was angry because at the same time I was blaming those who had captured us, I was blaming the British government, why don’t you do anything about it?
“I was really angry and that’s why I decided to send that voice message hoping that it would make a change.”
Asked about whether his wife received a response, Mr Ashoori said: “No and it took Richard on a hunger strike.”
Richard Ratcliffe, the husband of Ms Zaghari-Ratcliffe, went on hunger strike twice during his wife’s detention.
Asked again whether his wife had heard back from Mr Johnson, Mr Ashoori said: “No. Unfortunately. She made many attempts and all of them were unsuccessful.”
Now Mr Johnson wants to meet them, Mr Ashoori said.
“Last night, we received a letter, now he’s eager to see us. How would you interpret that?” he said on the programme.
“I think that it’s a bit of opportunism involved in it at the same time as all of this has happened under his command.
“So, one could argue that it was the British government, the present British government, that succeeded in doing that which is correct — at the same time you could say that why didn’t you contact us, my family, and now you are eager to do that?
“How would you expect us to absorb that? How would you expect us to think of you with this letter now? Why couldn’t this letter be sent five months ago, a year ago, two years ago? Why now?”
Asked if he will see Mr Johnson, he said: “I’m not sure.”
“I agree with Nazanin 100 per cent. She in fact put her finger on the right button by saying that,” Mr Ashoori said.
“She should have been here years ago if that debt was paid. That wasn’t a ransom, that was a debt that the British government owed.
“It should have been paid and if it was paid, perhaps none of this would have happened. So, yes, I feel a bit angry.”
Ms Zaghari-Ratcliffe said it had taken too long for the UK government to pay a £400 million ($527 million) debt to Iran, which helped secure her release.
Speaking about his time in Evin prison, Mr Ashoori said: “Literally, that was the valley of hell.
“Because in addition to your own suffering, you see the suffering of all the people who are around you.
“Each of them in their own different way. Marriages are breaking up. Families are disintegrating.
“And I was reasoning with myself that when I know that I am innocent, I am here, so everybody else can be innocent and be there.”