U.S. President Donald Trump said Wednesday that Iran was making significant concessions in ongoing negotiations, expressing optimism ahead of a new round of talks scheduled for next week.

"The war is going very well. As you know, we're winning by a lot. Iran is making very big concessions.

"We'll see what happens - but it has been very, very, very powerful," Trump told reporters at the Capitol.

Last week, Trump and Iranian President Masoud Pezeshkian electronically signed the "Islamabad Memorandum of Understanding," which is intended to pave the way for ending the war launched by Washington and Tel Aviv against Iran on Feb. 28.

Under the deal, Washington and Tehran are due to hold negotiations for 60 days, with the possibility of an extension, aimed at reaching a final agreement covering Iran's nuclear program and international sanctions.

Pakistan, the mediator, said the technical-level talks will resume next week, following a temporary pause.

Secretary of State Marco Rubio said Wednesday that the U.S. expects Iran to comply with its obligations under the interim deal.

"The president has been very clear -- they need to keep those commitments. If they do, we'll keep forward. If not, the president will have options at his disposal for what to do about it. Let's hope they keep those commitments," he said.