Mr. Biden said he had been informed of plans to help Israel if it was attacked, while Secretary of State Antony Blinken said authorities were working “around the clock” to prevent an escalation.
Tensions have heightened in the past week with the killing of Hamas political leader Ismail Haniyeh, for which Iran has blamed Israel and promised “severe” reprisals. Israel has not taken responsibility for the assassination.
Many countries, including the United States and the United Kingdom, have advised their people to evacuate Lebanon, where it is anticipated that Hezbollah, an Iran-backed militia and political movement, may play a part in any reaction.
According to US news site Axios, Mr Biden was told at Monday’s briefing that the time and manner of an Iranian attack were unknown. A day before, Mr Blinken reportedly told his G7 peers that Iran and Hezbollah could strike Israel within 24 to 48 hours.
In a statement issued following the briefing, Mr. Biden stated: “We received updates on threats posed by Iran and its proxies, diplomatic efforts to de-escalate regional tensions, and preparations to support Israel should it be attacked again.”
He also stated that plans were being taken to respond to attacks on US personnel “in a manner and place of our choosing”. On Monday, seven US servicemen were hurt in an apparent rocket attack on a US military installation in Iraq.