Iran has cautioned that a final agreement with the United States remains out of reach despite progress in negotiations aimed at ending the Middle East conflict.

The warning came on Monday following renewed optimism from Washington that a deal could be achieved soon.

Global oil prices fell after US Secretary of State Marco Rubio suggested an agreement could be reached within the day.

“We thought we might have some news last night, maybe today,” Rubio told reporters during a visit to New Delhi.

“We have what I think is a pretty solid thing on the table in terms of their ability to open up the straits, get the straits open,” he said.

“We’re either going to have a good agreement or we’re going to have to deal with it another way. We’d prefer to have a good agreement.”

However, Iran’s Foreign Ministry spokesman, Esmaeil Baqaei, downplayed expectations of an imminent breakthrough.

“It is correct to say that we have reached a conclusion on a large portion of the issues under discussion,” Baqaei told a weekly press briefing.

“But to say that this means the signing of an agreement is imminent — no one can make such a claim.”

The US and Iran have observed a ceasefire since April 8 while diplomatic efforts continue to seek a negotiated settlement.

Despite the truce, Iran has maintained control measures over Gulf shipping through the Strait of Hormuz, while the US Navy has continued operations around Iranian ports.

Baqaei also defended Iran’s collection of service charges on maritime traffic through the Strait of Hormuz, rejecting suggestions that Tehran was imposing tolls.

“The services that are provided — navigational services in addition to the measures necessary to protect the environment of the Strait of Hormuz, the Persian Gulf and the Sea of Oman — require the collection of certain fees,” he said.

US President Donald Trump earlier said negotiators had been instructed not to rush talks.

“If I make a deal with Iran, it will be a good and proper one,” Trump wrote on Truth Social.

“It isn’t even fully negotiated yet.”

Israeli Prime Minister Benjamin Netanyahu also said he and Trump agreed that any final arrangement with Iran must address concerns over Tehran’s nuclear programme.

Iranian officials, however, maintain that discussions around uranium enrichment and nuclear activities have been postponed until after an initial agreement is reached.

The conflict, which began after US and Israeli strikes on Iran on February 28 and subsequent Iranian missile and drone attacks, has disrupted global energy markets.

Although crude oil prices remain elevated, renewed optimism over diplomacy triggered fresh declines on Monday.

North Sea Brent crude and West Texas Intermediate crude dropped to $99 and $92.10 per barrel respectively.

Meanwhile, diplomatic efforts expanded to China, where Pakistan’s Prime Minister Shehbaz Sharif met Chinese President Xi Jinping in Beijing as part of wider mediation efforts involving regional powers.

“The world is passing through a critical moment,” Sharif said during the meeting.

“Things are moving in the right direction. I would like to thank China’s support to promote peace.”