Secretary of State Marco Rubio spoke with Lebanese President Joseph Aoun and Israeli Prime Minister Benjamin Netanyahu regarding ongoing negotiations between the two countries, a U.S. official told ABC News, and as Israel expanded its offensive against the Iran-backed Hezbollah militia in southern Lebanon.

The U.S., the official said, proposed that Israel would refrain from escalation in the Lebanese capital Beirut in exchange for Hezbollah’s halt of all attacks on Israel. That step, the official said, “would create space for gradual de-escalation and an effective cessation of hostilities.”

Aoun “tried to advance this proposal and secure an agreement,” the U.S. official said, but was stymied by Lebanese Parliament Speaker Nabih Berri — the head of the Shiite Amal Movement and a longtime political ally of Hezbollah.

The official described Berri’s response as “evasive and disappointing,” and “placed the burden on Israel to stop shooting first.”

“Hezbollah is following Tehran’s lead. It clearly has no interest in the welfare of the Lebanese people. Iran wants to prolong the conflict in Lebanon so it can claim credit for ‘saving the day,'” the U.S. official said.

“The United States does not expect Israel to absorb ongoing attacks on its civilians by a terrorist organization. The fastest way to de-escalate and protect civilians on all sides is for Hezbollah to stop firing immediately,” the official added.

-ABC News’ Shannon K. Kingston