Iran's deputy foreign minister warned the United States on Thursday against intervening in the war to back up its ally Israel, adding that his country was ready to defend itself in case of escalation.

"If the United States wants to actively enter the field in favor of the Zionist regime, Iran will have to use its tools to both teach a lesson to aggressors and defend its national security and national interests," said deputy foreign minister Kazem Gharibabadi, according to state TV.

Gaza's civil defense agency said that Israeli forces on Thursday killed at least 18 people, including 15 who had gathered near an aid distribution site in central Gaza.

Civil defence official Mohammad al-Mugghayyir told AFP that "18 people have been killed due to ongoing Israeli shelling on the Gaza Strip since dawn today, 15 of whom were waiting for aid", adding that the remaining three were killed by shelling near Gaza City.

Israel's defense minister said Thursday that Iran's supreme leader Ayatollah Ali Khamenei "can no longer be allowed to exist" after an Israeli hospital was hit during an Iranian missile attack.

"Khamenei openly declares that he wants Israel destroyed -- he personally gives the order to fire on hospitals. He considers the destruction of the state of Israel to be a goal," Israel Katz told journalists in Holon near Tel Aviv. "Such a man can no longer be allowed to exist."

Russian President Vladimir Putin and his Chinese counterpart Xi Jinping on Thursday strongly condemned Israeli attacks on Iran in a phone call, the Kremlin said, adding that both leaders called for a diplomatic solution to the conflict.

"Both sides adhere to identical approaches, strongly condemn Israel's actions," Kremlin aide Yuri Ushakov told reporters, adding that Moscow and Beijing believed the end to the hostilities "should be achieved exclusively by political and diplomatic means".

Russian President Vladimir Putin will visit China later this year for a regional summit, talks with leader Xi Jinping and commemorations marking 80 years since the end of World War II in Asia, the Kremlin said Thursday.

Putin will attend a summit of the Shanghai Cooperation Organization in Tianjin on August 31-September 1, before heading to the WWII events scheduled in Beijing for September 3, Kremlin aide Yuri Ushakov told reporters.

The U.S. special envoy for Syria Tom Barrack visited Lebanon on Thursday and warned Hezbollah against getting involved in the war between its main backer Iran and Israel.

Barrack is of Lebanese origins and is also the U.S. ambassador to Turkey. He has said that he will temporarily replace Morgan Ortagus as Washington's special envoy to Lebanon. During his first official visit to Lebanon on Thursday he met with President Joseph Aoun, Speaker Nabih Berri and Prime Minister Nawaf Salam.

U.S. President Donald Trump has told aides he has approved attack plans but is holding off to see if Iran will give up its nuclear program, the Wall Street Journal reported overnight.

He is due to receive an intelligence briefing on Thursday, a U.S. holiday, the White House said, while top U.S. diplomat Marco Rubio will meet his UK counterpart for talks expected to focus on the conflict.

U.S. President Donald Trump lashed out Wednesday at the Federal Reserve for not cutting interest rates, calling the central bank's leader "stupid" and insisting that there is "no inflation" despite worries over fresh tariffs.

"We have a stupid person, frankly, at the Fed, he probably won't cut today," Trump said, hours before the Fed was due to release its latest interest rate decision. "We have no inflation, we have only success, and I'd like to see interest rates get down."

President Donald Trump left the question of whether the United States will join Israeli strikes on Iran up in the air Wednesday, as he said that Tehran had reached out to seek negotiations.

"I may do it, I may not do it. I mean, nobody knows what I'm going to do," Trump told reporters as he supervised the installation of a new flagpole on the White House South Lawn.

Tropical storm Erick, bearing down on the southwestern coast of Mexico on the Pacific Ocean, strengthened into a hurricane Wednesday, the US National Hurricane Center said.

The hurricane is 255 kilometers (155 miles) from the town of Puerto Angel in the southern Mexican state of Oaxaca and is packing maximum sustained winds of 120 kilometers an hour (75 mph), the meteorological center said.