The husband of a British-Iranian woman jailed in Iran said there has been "no breakthrough" in efforts to secure her release after talks with Boris Johnson.
Richard Ratcliffe said his wife was being used as a "chess piece" in foreign policy and urged the government to be "tougher" with Tehran.
Nazanin Zaghari-Ratcliffe has been detained for almost four years over spying allegations she denies.
Her five-year-old daughter was also at the meeting at No 10 on Thursday.
Mr Johnson has previously said he would leave "no stone unturned" to help free her.
Mr Ratcliffe last met the prime minister when he was foreign secretary in 2017.
That meeting came shortly after Mr Johnson had to apologise after wrongly suggesting that Mrs Zaghari-Ratcliffe had been training journalists at the time of her arrest.
She has always maintained she was in Iran visiting relatives.
Thursday's meeting followed the US killing of Iran's top military leader Qasem Soleimani.
Holding the hand of his daughter, Gabriella, outside No 10, Mr Ratcliffe said he urged the prime minister to be "brave" in his dealings with Iran - and that relations between two countries must improve.
Mr Johnson is "personally committed" to her case, he said, and was "touched" when he gave him a wallet that Mrs Zaghari-Ratcliffe had made in prison.
But Mr Ratcliffe added that "sympathy isn't enough" and that the prime minister did not apologise for the mistake he made as foreign secretary.
"I don't stand here hopeful, if I'm honest. I stand here with my wife still in prison and things aren't moving," he said.
"I will think carefully about what I tell her on the phone on Saturday."
He has previously raised concerns that the recent escalation in tensions could make matters worse for his wife.
Ahead of the meeting, which the foreign secretary also attended, the prime minister's spokesman said Mrs Zaghari-Ratcliffe's continued detention was "inhumane and unacceptable" and the UK continued to "take every opportunity" to raise her case with the Iranian government.
It comes as the Court of Appeal in London prepares to hear a case that could resolve a decade-long financial dispute between the UK and Iran.
The dispute is over the interest due on a debt owed by Britain to Tehran for an arms deal in the 1970s that was never fulfilled.
Mr Ratcliffe said he was told at the meeting that the government is trying to resolve "other issues" but that they are "complicated".
Speaking in the Commons, the couple's MP, Labour's Tulip Siddiq, urged the government to settle the debt with Iran, accusing it of "unforgiveable" behaviour.
However, Commons Leader Jacob Rees-Mogg said the issue was "extraordinarily difficult" because the government could not be seen to be paying money to allow the release of people who had been illegally detained.
"The risk that would cause to other Britons travelling abroad would be very considerable," he said.
"The law must take its course in relation to the money that was deposited here but it would be absolutely wrong to connect the two issues."
Mrs Zaghari-Ratcliffe, 41, remains on medication for depression and on beta blockers - medicines which slow down the heart - for the panic attacks she's been suffering in jail, her husband said.
The dual national has been detained since 2016, when she took her British-born daughter Gabriella to Iran to visit her parents. She was sentenced to five years in prison for spying.
Her family and the UK government has always maintained her innocence and she has been given diplomatic protection by the Foreign Office - meaning the case is treated as a formal, legal dispute between Britain and Iran.
While he was foreign secretary, Mr Johnson mistakenly said that Mrs Zaghari-Ratcliffe had been in Iran training journalists when she was arrested.
Four days later Mrs Zaghari-Ratcliffe was summoned to an unscheduled court hearing during which Mr Johnson's comments were cited as proof she was engaged in "propaganda against the regime".