Boris Johnson has derided critics of a comment he made that could lengthen the sentence of a British woman jailed in Iran.
The Foreign Secretary said people attacking him over the blunder were "deflecting blame and accountability" from the Middle Eastern country – which was "truly responsible".
He said it was "simply untrue" there was any connection between his mistaken remark and the legal proceedings against Nazanin Zaghari-Ratcliffe.
Mrs Zaghari-Ratcliffe has been jailed in Iran since April 2016. Her family had called on Mr Johnson to correct his recent claim she was teaching journalists at the time she was arrested – rather than on holiday.
Mr Johnson called the country's foreign minister to insist it was "absolutely not the case", but dodged offering an apology.
He told the House of Commons on Tuesday: "What everybody in this House wants to see is Nazanin Zaghari-Ratcliffe released – and that is exactly what the Foreign Office is working for; that is what we've been working for solidly over the last 18 months."
He later added: "Of course I am sorry if any words of mine have been so taken out of context or misconstrued."
But Tory backbencher Anna Soubray responded that his "lack of contrition is as shameful as the original error".
"Boris Johnson doesn't understand magnitude of the job & responsibility he holds," she tweeted.
While Labour MP Chris Bryant commented: "I fear that if he can't show some contrition today, then the honest truth is he shouldn't be in his job because our people aren't safe."
But Foreign Affairs committee member Nadhim Zahawi said the Iranian authorities were the sole ones to blame for Mrs Zaghari-Ratcliffe's incarceration.
"If our words really do matter then it's only right that we don't play party politics," he said.
Mr Johnson also confirmed he would travel to Iran before the end of the year to discuss Mrs Zaghari-Ratcliffe's case and hopefully visit her in prison.
The row and its fallout has led to calls for the Foreign Secretary to consider his position – should Mrs Zaghari-Ratcliffe have her sentenced increased.
International Trade Secretary Liam Fox told Sky News on Tuesday: "I don't believe it is a serious gaffe.
"I think people in the Iranian regime, which is a very brutal regime, are using this as an excuse to hold a UK citizen in the most tenuous, if not illegal, circumstances."