Chinese Foreign Ministry spokesperson Guo Jiakun told reporters on Tuesday that the U.S. blockade of Iran's Strait of Hormuz ports "will only exacerbate tensions, undermine the already fragile ceasefire and further impact the safety of navigation."

Guo described the blockade, which began on Monday, as "a dangerous and irresponsible act."

Beijing, Guo said, "believes that only a comprehensive ceasefire can fundamentally create conditions for easing tensions in the Strait of Hormuz."

"China urges all parties to abide by the ceasefire agreement, focus on the general direction of dialogue and negotiations and take concrete actions to promote regional de-escalation and restore normal navigation in the Strait of Hormuz as soon as possible," Guo said.

-ABC News' Karson Yiu

In a series of diplomatic meetings in Beijing on Tuesday with Spanish Prime Minister Pedro Sanchez and Abu Dhabi's Crown Prince Sheikh Khaled bin Mohamed bin Zayed Al Nahyan, Chinese President Xi Jinping voiced his concern about recent developments in the Middle East and promoted China as a responsible and stable partner.

Xi did not mention the U.S. or President Donald Trump by name while meeting either leader.

"The world today is rife with chaos and faces a contest between justice and power," Xi said while meeting Sanzhez, adding that the two nations should work together to "oppose the world's regression to the law of the jungle."

Xi told Sanchez, "How a country treats international law and the international order reflects its worldview, view of order, values and sense of responsibility."

In his meeting with Abu Dhabi's crown prince, Xi played up China's efforts to promote peace talks and said that Beijing would continue to do so.

Xi also proposed a four-point framework for "promoting peace and stability in the Middle East."

It called for adherence to the principles of peaceful coexistence, national sovereignty, the international rule of law and the coordination of development and security.

The proposal is a regional facsimile of the Global Security Initiative that Xi unveiled in 2022 intended as an alternative to the existing U.S.-led security architecture, but which gained little traction at the time.

-ABC News' Karson Yiu

The U.S. proposed a 20-year minimum suspension on Iranian uranium enrichment rather than a permanent end to enrichment amid negotiations to end the war with the country, a source familiar with the negotiations told ABC News on Monday.

The source said that in addition to the suspension, the U.S. also suggested "all kinds" of other restrictions but did not immediately elaborate on what they were.

The news comes as The New York Times reported on Monday that the U.S. had asked for a 20-year suspension, with the Iranians formally responding on Monday that they would agree to suspend enrichment for up to five years. The paper reported that the president had rejected that offer.

The White House did not respond to ABC News' request for comment on the Iranian proposal nor the president’s reaction to it.

-ABC News' Nicholas Kerr

Secretary of State Marco Rubio will now participate in the talks between Israeli and Lebanese ambassadors in D.C. on Tuesday, according to a State Department official.

"This conversation will scope the ongoing dialogue about how to ensure the long-term security of Israel's northern border and to support the Government of Lebanon's determination to reclaim full sovereignty over its territory and political life," the official said. "Israel is at war with Hizballah, not Lebanon, so there is no reason the two neighbors should not be talking."

-ABC News' Shannon K. Kingston

Nine vessels have been turned around at the Strait of Hormuz during the first 48 hours of the U.S. blockade, complying with U.S. orders, according to U.S. Central Command.

"During the first 48 hours of the U.S. blockade on ships entering and exiting Iranian ports, no vessels have made it past U.S. forces," according to CENTCOM.