Israel and Lebanon agreed on Tuesday to begin direct talks following a landmark meeting between the Israeli and Lebanese ambassadors to the United States, weeks after Hezbollah pulled Lebanon into the Middle East war with rocket fire at Israel in support of its backer Iran.

"Direct negotiations with the enemy are a grave sin and a grave error," Hajj Hassan said from his parliamentary office.

US President Donald Trump said the Lebanese and Israeli "leaders" would speak on Thursday, but Lebanese President Joseph Aoun's office has not confirmed the call, stressing the importance of a ceasefire before any direct negotiations.

An official source told AFP that Aoun had rejected a US request for a direct phone call with Israeli Prime Minister Benjamin Netanyahu on Thursday.

Hajj Hassan said direct talks serve "no interest for the country or its citizens... so how can there be contact at the level Trump mentioned?"

He criticised the government for agreeing to negotiations before securing a ceasefire in Lebanon.

"If they are unable to uphold a single condition called a ceasefire, how will they negotiate with the Zionist entity (Israel) under American auspices?" he said.

The Lebanese government "insists on reaching a ceasefire through the Israelis and the Americans... and not through Iran," he said.

Israel has been carrying out huge strikes on Lebanon and a ground invasion in the country's south, while Washington and Tehran have been at odds on whether a fragile Middle East ceasefire applies to Lebanon.

Hajj Hassan accused Lebanese officials of refusing to let the country be part of a regional ceasefire due to "unjustified blind hatred of Iran".

He urged Lebanese authorities to halt "this series of useless concessions... to a treacherous and cunning enemy, and to a hypocritical, deceitful, evasive and lying America".

Iran is Hezbollah's main backer, and for decades has supplied the group with money and weapons.

On Thursday, Iran's parliament speaker Mohammad Bagher Ghalibaf told his Lebanese counterpart and Hezbollah ally Nabih Berri that "for us, a ceasefire in Lebanon is just as important as a ceasefire in Iran".