US President Donald Trump on Wednesday warned Iran against further uranium enrichment but left open the possibility the US could lift sanctions to pave the way to a meeting with President Hassan Rouhani.

Asked if he would ease crippling sanctions to help bring about a meeting with the Iranian leader, Trump replied “we will see what happens,” while warning it would be “very, very dangerous” for Iran to boost its enriched uranium stockpiles.

Trump said that he believes Iran would like to make a deal because “they have tremendous financial difficulty, and the sanctions are getting tougher and tougher.”

“We cannot let Iran have a nuclear weapon, and they never will have a nuclear weapon,” he said.

“If they are thinking about enrichment, they can forget about it. Because it’s going to be very dangerous for them to enrich. Very, very dangerous, okay?”

Rouhani has dismissed meeting with Trump, insisting that Washington must lift the sanctions it has imposed on Iran.

Earlier on Wednesday, during a meeting with his Cabinet, Rouhani said, “The Americans must understand that bellicosity and warmongering don’t work in their favour. Both… must be abandoned.”

Last week, President Rouhani had ruled out holding any bilateral talks with the United States and threatened to further cut Iran’s commitments to a nuclear deal within days.

The US said that the Iranian space launch vehicle technology is “virtually identical and interchangeable with those used in ballistic missiles,” including ways of controlling a missile during its flight.

The US also warned the “international scientific community that collaborating with Iran on space launch vehicles could contribute to its ballistic missile program.”

In response to the US, Iran said that its space program is aimed at building rockets to launch telecommunications satellites. Iran has fired two such satellites into orbit since 2013. But three other attempts this year have failed, including one rocket that blew up on the launch pad last week.

Tehran and Washington have been at loggerheads since May last year when US President Donald Trump unilaterally withdrew from the nuclear deal and began reimposing crippling sanctions.