The Iranian president on Monday urged all citizens to put aside differences and unite against Israel as conflict rages between the two arch-foes.

"Every difference, issue, and problem that has existed must be put aside today and we must stand strong against this genocidal criminal aggression with unity and coherence," Masoud Pezeshkian said, addressing parliament.

Iran's chief justice Gholamhossein Mohseni Ejei on Monday vowed swift trials for people arrested on suspicion of collaborating with Israel, as intense fighting raged between the two sides.

"If someone is arrested for having ties to and collaborating with the Zionist regime, their trial and punishment should be carried out and announced very quickly, in accordance with the law and given the war conditions," Ejei said, quoted by Tasnim news agency.

Iran on Monday urged Britain, France and Germany to pressure Israel to stop its deadly attacks on Iran as fighting raged between the two foes for a fourth day.

"Germany, France and England should have very clearly condemned the Zionist regime's crimes, especially against the Natanz nuclear facility," said foreign ministry spokesman Esmaeil Baqaei, adding that European powers should focus on "stopping the aggression" and holding Israel "accountable".

Iran urged the UN's International Atomic Energy Agency to condemn Israeli attacks on nuclear sites in the Islamic republic during an emergency meeting on Monday.

"We expect the (IAEA) Board of Governors and the Director General to take a firm position in condemning this act (attacking nuclear facilities) and holding the regime (Israel) accountable," said foreign ministry spokesman Esmaeil Baqaei during a weekly press briefing.

Iran has yet to decide whether to join a sixth round of nuclear talks with the United States on Sunday, state media reported, as Israel and Iran traded fire for a second day.

Israeli strikes on Iran on Friday and Tehran's vows of reprisals have brought the two Middle East adversaries closer to an all-out war, which also threatens to draw in the United States, at least to some degree.

So how do the militaries of Iran and Israel stack up against each other?

Russian President Vladimir Putin condemned Israel's wave of strikes launched at Iran, the Kremlin said on Friday, as he held separate phone calls with Israeli Prime Minister Benjamin Netanyahu and Iranian President Masoud Pezeshkian.

"Vladimir Putin stressed that Russia condemns Israel's actions, which violate the UN Charter and international law," the Kremlin said in a statement, adding that Putin told Netanyahu of his "readiness to provide mediation" to prevent further escalation.

Iranian air defenses intercepted "projectiles" over the capital Tehran on Friday, state media said, as Israel vowed to keep up pressure after a wave of strikes on military and nuclear sites.

"Enemy projectiles were intercepted by the Tehran air defense," state news agency IRNA said, with another agency, ISNA, reporting that "the air defense systems of Tehran successfully shot down targets".

Several explosions were heard in Tehran and surrounding areas Friday evening, Iranian state media reported, more than 12 hours after a massive wave of Israeli attacks on the country.

"There were reports of explosions heard in the west of Tehran province," in the cities of Shahriar and Malard and around the neighborhood of Chitgar in Tehran city, state news agency IRNA reported, while Mehr agency reported a blast in Pakdasht southeast of the capital.

Israeli leaders cast a blistering attack on the heart of Iran’s nuclear and military structure as necessary to head off an imminent threat that Iran would build nuclear bombs, though it remains unclear how close the country is to achieving that or whether Iran had actually been planning a strike. Iran maintains its nuclear program is for civilian purposes only.

"This is a clear and present danger to Israel’s very survival,” Israeli Prime Minister Benjamin Netanyahu claimed as he vowed to pursue the attack for as long as necessary to “remove this threat.”