The U.S. is deploying additional military might in the Middle East as a defensive measure with a goal of de-escalating tensions in the region, a White House official said on Sunday.

Regional tensions have increased following the assassination on Wednesday of Ismail Haniyeh, the leader of the Palestinian Islamist group Hamas, in Tehran a day after an Israeli strike in Beirut killed Fuad Shukr, a senior military commander from the Lebanese group Hezbollah. Both groups are backed by Iran.

There are mounting fears that Israel's war against Palestinian militants in Gaza, which began last October after attacks on the Jewish state, could escalate into a wider Middle East conflict. Iran and Hamas have blamed Israel for Haniyeh's killing in the Iranian capital, and they, together with Hezbollah, have vowed revenge. Israel has not claimed or denied responsibility.

U.S. President Joe Biden will convene his national security team in the situation room on Monday to discuss developments in the Middle East, the White House said, adding that he would speak with Jordan's King Abdullah as well.

U.S. news service Axios reported that U.S. Secretary of State Antony Blinken told his counterpart from G7 countries that Iran and Hezbollah could start attacking Israel as early as Monday, citing three sources briefed on the call. But Blinken, according to Axios, said it was unclear how Iran and Hezbollah would attack and did not know the exact timing.

When asked about the report, the State Department referred to a readout of the call, where it said the ministers discussed "the urgent need for de-escalation in the Middle East."

The Pentagon said on Friday it would deploy additional fighter jets and Navy warships to the region.

"The overall goal is to turn the temperature down in the region, deter, and defend against those attacks, and avoid regional conflict," Jonathan Finer, the White House's deputy national security adviser, said on CBS' "Face the Nation" program.

The U.S. and Israel are preparing for every possibility, Finer added.

There was a "very close call" of regional conflagration in April, Finer said, when Iran launched an attack on Israeli territory with drones and missiles after what it called an Israeli strike on its consulate in Damascus on April 1 that killed seven officers of the Islamic Revolutionary Guard Corps in the Syrian capital.

The U.S. wants to be prepared should that situation rise again, Finer added.

In a call with his Israeli counterpart, the Pentagon said U.S. Defense Secretary Lloyd Austin reiterated the United States' support for Israel's security and "right to self-defense against threats from Iran, Lebanese Hizballah (Hezbollah), Houthis, and other Iranian-backed terrorist groups."

Blinken spoke with Iraqi Prime Minister Mohammed Shia al-Sudani on Sunday and emphasized "the importance of all parties taking steps to calm regional tensions, avoid further escalation, and advance stability," the State Department said.