Donald Trump warned Iran of the consequences of breaching the 2015 nuclear deal.

President Donald Trump accused Iran on Wednesday of secretly enriching uranium for a long time and warned that U.S. sanctions will be increased soon, as the U.N. nuclear watchdog held an emergency meeting on Tehran's breach of a nuclear deal.

"Iran has long been secretly 'enriching,' in total violation of the terrible 150 Billion Dollar deal made by John Kerry and the Obama Administration. Remember, that deal was to expire in a short number of years. Sanctions will soon be increased, substantially!" Trump said on Twitter.

The United States used an emergency meeting of the U.N. International Atomic Energy Agency's board on Wednesday to pressure Iran over breaches of the 2015 international nuclear deal, accusing it of extortion and pledging to continue sanctions while still offering to hold talks.

In the past two weeks Iran has breached two limits central to the 2015 nuclear deal, which aimed to extended the time Iran would need to obtain enough fissile material for a nuclear weapon. President Hassan Rouhani said on Wednesday that Iran's measures were within the framework of the deal, which Trump pulled the United States out of last year.

Washington, meanwhile, is set on isolating Iran to force it to negotiate over the nuclear pact, its missile program and its actions in the region.