Iran has called in foreign ambassadors based in Tehran to warn of the country’s moral duty to punish Israel for what it sees as its “adventurism” and law-breaking in assassinating Ismail Haniyeh, the Hamas leader, a week ago in the Iranian capital.

Iran has also secured an emergency meeting of the Organisation of Islamic Cooperation (OIC) on Wednesday where it will try to press Arab states to back its right to take reprisal actions against Israel.

Many leaders in the Gulf are willing to condemn Israel’s actions but have also been calling for Iran to show restraint. The meeting will be held at the OIC headquarters in Jeddah, Saudi Arabia.

Israeli leaders have said they are prepared for an Iranian-led attack. The defence minister, Yoav Gallant, said in response to mounting Iranian threats on Monday that the Israeli military was ready for a “swift transition to offence”, echoing comments by the prime minister, Benjamin Netanyahu, who said on Sunday the country was already engaged in a multi-front war with Iran and its allies.

Previous efforts by the deceased Iranian president Ebrahim Raisi to win the support of Gulf states for military action or direct economic sanction failed. Raisi died in a helicopter crash in May.

President Joe Biden met his national security team in Washington, after which the US secretary of state, Antony Blinken, repeated calls for a ceasefire in Gaza and urged all parties to refrain from escalating.

Blinken was earlier reported to have indicated he was expecting Iran to launch a series of coordinated strikes as soon as Monday.

Tehran airport cancelled a number of incoming and outgoing flights on Sunday evening, suggesting it was fearful that civil aircraft may be caught up in military activity.

In a previous military exchange in January 2020 between the US and Iran, the Islamic Revolutionary Guards Corps (IRGC) mistakenly shot down a Ukrainian civil flight from Tehran to Kyiv, killing all 176 occupants on board.

Russia’s security council secretary, Sergei Shoigu, arrived in Tehran on Monday for talks with the Iranian leadership, including the president, Masoud Pezeshkian. Shoigu, previously Russia’s defence minister, was removed from that post by Vladimir Putin but remains central to Russia’s defence cooperation with Iran. There is no sign that Russia is urging restraint.

Iran is trying to portray its planned missile strikes as necessary to try to re-establish regional deterrence after the US’s failure to control its ally Israel.

In a meeting with foreign diplomats, the acting foreign minister, Ali Bagheri, said: “We all have a moral duty and responsibility not to remain silent in the face of the occupation, displacement and genocide of the Palestinian nation.” He added: “Indifference and appeasement in the face of evil and injustice is a kind of moral negligence and causes the spread of evil.”

Speaking at his weekly briefing, the Iranian foreign ministry spokesperson, Nasser Kanaani, said action from Tehran was inevitable.

“Iran seeks to establish stability in the region, but this will only come with punishing the aggressor and creating deterrence against the adventurism of the Zionist regime [Israel],” said Kanaani, as he called on the US to stop supporting Israel and added that the international community had failed in its duty to safeguard stability in the region and should support the “punishment of the aggressor”.

He added: “Terror is in the essence of the Zionist regime, and its survival depends on the continuation of the approach of state terrorism. The world should strongly condemn this crime, secondly, it should support the punishment of the aggressor and avoid any approach that means supporting the aggressor.”

His remarks were directed at Arab states, including Jordan, that cooperated with western powers on 13 April of this year to reduce the impact of the Iranian attack on Israel in April following the assassination of IRGC commanders in an Iranian consulate in Damascus on 1 April.

Jordan’s King Abdullah II spoke by phone to Biden, while the country’s foreign minister Ayman al Safadi called his British counterpart, David Lammy, as part of the flurry of diplomacy.

Safadi warned that the crisis would not end until Israel is persuaded to cease its military operations in Gaza, and British officials came away with the impression that it is almost inconceivable that Jordan will succumb to US pressure and agree to help shoot down any Iranian missiles flying over Jordanian soil towards Israel.

Inside Iran, those who have counselled caution, or even suggested that the country could diplomatically exploit Israel’s overreach, seem to have lost out to those who have argued that there should be a coordinated attack on Israel mounted by Hezbollah, Hamas, Iraqi militant groups, the Houthis in Yemen and Iran itself.

In the April episode, it took Iran 12 days to decide and launch its response. It used that time not only to calibrate its response, but also to send out messages that it was not seeking a regional war, messages that in turn led the US to restrain Israel in its own response.

Some of this messaging about the scale of both sides’ reaction is absent, but the longer the pause between the assassination of Haniyeh and Iran’s response, the more time exists for diplomacy to reduce the scope for misunderstandings.

On Monday, the top IRGC commander, Hossein Salami, repeated the group’s threat that Israel “will receive punishment in due time”, adding that Israel was digging its own grave.

A base hosting US troops in Iraq came under rocket fire on Monday, after an American strike on 30 July killed four pro-Iran Iraqi fighters.

Meanwhile, fighting continued to rage on Monday in the Gaza Strip and on the blue line separating Israel and Lebanon.

The Lebanese militant group Hezbollah said it launched an early morning drone attack on northern Israel which the Israeli military said wounded two of its troops, while Lebanon’s state-run National News Agency said an Israeli drone strike near a cemetery in a southern village killed two people, including a paramedic.

In Gaza, Palestinian officials said an Israeli airstrike killed five members of Gaza’s Hamas-run police force, who were securing an aid convoy. The strike on a civilian target took place after Israeli attacks hit two schools and a hospital complex in Gaza on Sunday, killing at least 30 people.

Israel’s military said it had struck Hamas command centres at the schools, and that the hospital strike targeted a militant, without providing further details or evidence.

The ability of Hamas to launch rocket and mortar attacks at Israeli territory has dwindled over the last 10 months of fighting, but at least 15 projectiles were fired from Gaza on Monday, wounding one person, the Israeli military said.

Haniyeh’s assassination and its aftermath is widely expected to negatively impact internationally mediated talks aimed at brokering a ceasefire and hostage and prisoner release deal in the Gaza war.

There is mounting concern in Israel’s defence establishment that Netanyahu is avoiding taking decisions on the negotiations for political reasons, according to angry exchanges leaked over the weekend to the Israeli press.