The Iranian military's Khatam Al-Anbiya Central Headquarters said in a statement on Monday that Iran's retaliation against Israel for attacks on Lebanon has concluded, but warned that if hostilities continue, Iran's response will be more severe.

"A painful response was delivered to the Israeli regime, and the suspension of armed forces operations is announced," the statement said, according to Iranian state media.

"If the aggressions and provocations continue, including in southern Lebanon, much more severe and decisive actions than before will follow," the statement added.

-ABC News' Somayeh Malekian

President Donald Trump said in a post to social media on Monday that Israel and Iran "are looking to do an immediate CEASEFIRE!"

"Final negotiations on 'Peace' are proceeding, subject to ignorance or stupidity getting in its way," Trump wrote, adding that the U.S. blockade of Iranian ports will remain until a deal is reached.

-ABC News' Fritz Farrow

An Israeli military official told ABC News on Monday that the Israel Defense Forces is "preparing for a range of options from several days to as long as it'll take," amid new direct exchanges between Israel and Iran that resumed on Sunday.

Iran has fired nearly 30 ballistic missiles toward Israel since Sunday evening, according to an Israeli military official. Additionally, the Houthis fired two ballistic missiles, only one of which reached Israeli territory.

Israeli aircraft carried out strikes on military targets in Iran on Monday morning, including on Iranian air defense systems, the official said. The IDF also hit a petrochemical plant in southwestern Iran which was used for making chemicals for ballistic missiles, an Israeli military official said.

-ABC News' Victoria Beaule and Jordana Miller

Sadegh Larijani, the head of Iran's Expediency Discernment Council and the brother of slain senior official Ali Larijani, said on Monday that Tehran's attacks on Israel "in defense of Lebanon" indicate "the formal declaration of a strategic doctrine."

Larijani said the Iranian attacks "sent a clear message that if one side of the Axis of Resistance is attacked, it will trigger a response that extends beyond geographical borders and will change the region's equations," as quoted by the semi-official Tasnim News Agency.

The Axis of Resistance refers to the Iranian-led grouping of militias spread around the Middle East through which Tehran has traditionally sought to build deterrence against and erode the influence of Israel, the U.S. and their regional partners. Lebanese Hezbollah is a key part of the axis.

-ABC News' Somayeh Malekian

President Donald Trump told Axios that after Iran and Israel traded strikes Sunday night for the first time since the U.S. and Iran agreed to a ceasefire in April, he warned Israeli Prime Minister Benjamin Netanyahu that he might be “on [his] own very soon” if war resumed.

"I said, 'Bibi, you better be careful, or you will be on your own very soon,'" Trump said in a phone interview on Monday.

Axios reported that Trump called Netanyahu on Sunday evening and asked him not to retaliate against Iran after they launched attacks at Israel.

Trump claimed in the interview with Axios that Israel "gave us very late notice" about Sunday's strikes.

"They were already on their way. But eventually I had [the Israeli strike] limited," Trump said.

Trump also told Axios he received calls from five different countries in the region asking him to press Netanyahu to stop.

"These countries were very concerned. They love the deal that we have been negotiating," Trump said.

Trump also claimed his administration received messages from the Iranians on Monday morning stating a willingness to stop shooting if Israel did the same.

"They called us and said that they are not doing any more attacks and asked us to tell Israel not to do any more attacks," Trump said.

-ABC News’ Isabella Murray