U.S. President Donald Trump said U.S. air strikes on Sunday "totally obliterated" Iran's main nuclear sites, as Washington joined Israel's war with Tehran in a flashpoint moment for the Middle East.

In a televised address to the nation from the White House, Trump warned that the United States would go after more targets if Iran did not make peace quickly.

Israel targeted "two centrifuge production sites" at Iran's Isfahan nuclear facility overnight in a second wave of strikes on the location since the start of the war, a military official said on Saturday.

Israel claimed on Saturday it has already set back Iran's presumed nuclear program by at least two years, a day after U.S. President Donald Trump warned that Tehran has a "maximum" of two weeks to avoid possible American air strikes.

U.S. President Donald Trump said overnight that Iran had a "maximum" of two weeks to avoid possible U.S. air strikes, indicating he could take a decision before the fortnight deadline he set a day earlier.

Hours of talks aimed at de-escalating fighting between Israel and Iran failed to produce a diplomatic breakthrough as the war entered its second week with a fresh round of strikes between the two adversaries.

At least 23 heavy Iranian missiles were fired at Israel on Friday afternoon, causing extensive damage in Tel Aviv and wounding at least 10 in Haifa, two of them seriously, after six missiles managed to penetrate Israel’s air defenses, Iranian and Israeli media reports said.

Video footage showed a missile causing a big explosion in Haifa, with Israel’s Channel 13 saying there are fears of a possible leakage of dangerous material.

Gaza's civil defense agency said Israeli forces killed at least 43 people on Friday, including 26 who had gathered near an aid distribution center, the latest in a string of deadly incidents targeting aid seekers in the Palestinian territory.

"Forty-three martyrs have fallen as a result of the ongoing Israeli bombardment on the Gaza Strip since dawn today, 26 of whom were waiting for humanitarian aid," Mohammad Al-Mughayyir, director of medical supply at the civil defense agency in Gaza, told AFP.

Israel and Iran exchanged strikes a week into their war Friday as President Donald Trump weighed U.S. military involvement and new diplomatic efforts got underway.

Trump has been weighing whether to attack Iran by striking its well-defended Fordo uranium enrichment facility, which is buried under a mountain and widely considered to be out of reach of all but America's "bunker-buster" bombs. He said he'll decide within two weeks whether the U.S. military will get directly involved in the war given the "substantial chance" for renewed negotiations over Tehran's nuclear program.

Thousands of people joined a protest against Israel in the Iranian capital on Friday after weekly prayers, chanting slogans in support of their leaders, images on state television showed.

"This is the Friday of the Iranian nation's solidarity and resistance across the country," the news anchor said. Footage showed protesters holding up photographs of commanders killed since the start of the war with Israel, while others waved the flags of Iran and the Lebanese militant movement Hezbollah.

French President Emmanuel Macron on Friday said France and other European powers would make an offer to Iran of a diplomatic solution to end the escalating conflict with Israel.

French Foreign Minister Jean-Noel Barrot will later Friday meet Iranian counterpart Abbas Araghchi in Geneva "to make a complete diplomatic and technical offer for negotiations," Macron told reporters, adding that France and allies Germany and the UK were "putting a diplomatic solution on the table".