Johnson’s comments came after he formally blamed the Islamic republic for attacks on oil facilities in Saudi Arabia, and as he prepares to meet the nation’s president Hassan Rouhani and Trump in separate meetings on Tuesday.
“Let’s do a better deal,” Johnson said in an interview at the residence of the UK consulate general in New York.
“I think there’s one guy who can do a better deal… and that is the President of the United States. I hope there will be a Trump deal.”
But Downing Street moved to stress that Johnson supports the nuclear deal.
“The PM supports the JCPoA,” a Government spokesman said.
“The Iranians aren’t currently in compliance and we need to bring them back into compliance. If there’s a way to do that, we’re open to discussing possible solutions.”
Johnson was talking after a terse exchange of words with Iran, saying Iran was responsible for the Aramco attacks with a “very high degree of probability”.
Iran countered by rejecting the PM’s remarks and criticising “fruitless efforts against the Islamic republic of Iran”.
The US and Saudi Arabia had already accused Iran of being behind the September 14 raids on the world’s largest oil processor and an oil field, causing a spike in prices.
But Johnson gave the first attribution of blame from the UK before landing in the US in the early hours of Monday UK time, as he flew to the States. Tehran has issued denials.