After a brief calm following heavy exchanges of strikes between Israel and the Lebanese group Hezbollah, fighting resumed Monday.

Iran’s foreign minister again referenced his country’s planned retaliation for the assassination of Hamas leader Ismail Haniyeh in Tehran.

Abbas Araghchi said late Sunday he made the remark in a phone conversation with Italian Foreign Minister Antonio Tajani.

"Iran’s reaction to the Israeli terrorist attack in Tehran will be definitive, measured and well-calculated," Araghchi wrote on X, formerly Twitter. "We do not fear escalation, yet do not seek it – unlike Israel."

Tajani, in a statement, called for restraint and a constructive approach to stop the cycle of military actions in the region, which risks bringing more suffering.

"It is important that Iran exercises moderation toward Hezbollah to avert escalation on the Lebanese-Israeli border, where Italian soldiers of the UNIFIL contingent are operating, and toward the Houthis to avoid increasing tensions in the Red Sea area, where Italy plays a leading role in the EU’s Aspides mission," he said.

This call came after Israel and Hezbollah, long backed by Iran, traded heavy fire early Sunday but stopped short of sparking a widely feared all-out war.

Meanwhile, high-level talks in Cairo aimed at securing a cease-fire and a hostage deal to temporarily end the 10-month Israel-Hamas conflict in Gaza ended Sunday without a final agreement, a U.S. official said.

However, discussions will continue at lower levels in the coming days to address the remaining gaps.

The official, who spoke on the condition of anonymity, said lower-level "working teams" will remain in Cairo to meet with mediators from the U.S., Qatar and Egypt in hopes of bridging remaining disagreements.

The talks included CIA Director William Burns and David Barnea, head of Israel’s Mossad intelligence agency.

A Hamas delegation was briefed by Egyptian and Qatari mediators but did not directly participate in the negotiations.