The United States said Friday it sought to degrade ammunition supplies of Iranian-linked militias with strikes in Syria but insisted it did not want to widen the Middle East conflict.

The Pentagon on Thursday announced air strikes on two sites in eastern Syria it said were used by Iran's elite Islamic Revolutionary Guard Corps (IRGC) after a string of attacks on US forces in Iraq and Syria since the start of the Israel-Hamas war.

"The purpose for those two sites that we targeted was to have a significant impact on future IRGC and Iran-backed militia group operations," National Security Council spokesman John Kirby told reporters Friday.

"It went right at storage facilities and ammo depots that we know will be used to support the work of these militia groups, particularly in Syria."

"The main goal was to disrupt that ability and also to deter — to prevent — future attacks," he said.

The White House earlier said that President Joe Biden had relayed a direct warning to Iran's supreme leader Ayatollah Ali Khamenei against militias' strikes on US troops in Syria and Iraq, where US forces are stationed as part of efforts against the Islamic State group, which also has clashed with Shiite Iran.

There have been at least 14 attacks on US and allied forces in Iraq and six in Syria since October 17, a period in which 21 American military personnel suffered minor injuries and one contractor died from a cardiac incident, according to the Pentagon.

The US strikes on Thursday were the first on Iranian interests since March, breaking a stretch of calm after the Biden administration opened quiet diplomacy with the US arch-enemy that led to a prisoner swap and conversations on Iran's disputed nuclear program.

The October 7 assault by Hamas and Israel's retaliatory strikes have inflamed the region. Iran's clerical leaders back Hamas, while the United States is the foremost ally of Israel.

Defense Secretary Lloyd Austin, in a statement Thursday, said that the strikes were "narrowly tailored" to protect US personnel.

"They are separate and distinct from the ongoing conflict between Israel and Hamas, and do not constitute a shift in our approach to the Israel-Hamas conflict," Austin said.

The Pentagon said Friday evening that its current assessment is the strikes did not cause casualties.

'Finger on the trigger'

In new pressure, the United States — which already considers Hamas and the Revolutionary Guards to be terrorist organizations — said it was imposing sanctions on a Hamas official based in Iran and members of the IRGC.

The Biden administration has vowed to target the finances of Hamas, which holds hundreds of millions of dollars in global assets, according to US Treasury Department estimates.

Iran also has a close relationship with Hezbollah, the Lebanese Shiite militia and political movement that has repeatedly fired at Israel but has so far stopped short of opening a full second front.

Iranian Foreign Minister Hossein Amir-Abdollahian said Friday that he has spoken with Lebanese and Palestinian militants and they "have their finger on the trigger" if Israel expands its ground operation into Gaza.

Speaking to US National Public Radio from the United Nations, Amir-Abdollahian said the militants' actions would be "much more powerful and deeper than what you've witnessed."

"Therefore I believe that if this situation continues and women and children and civilians are still killed in Gaza and the West Bank, anything will be possible," he said.

Amir-Abdollahian insisted, however, that militants would decide their own actions, saying, "We don't really want this conflict to spread out."

Addressing the General Assembly on Thursday, Amir-Abdollahian said that the Palestinians "as a nation under occupation" have the "legitimate right to resist the occupation using all available methods, including armed struggle."

Hamas militants on October 7 stormed out of the blockaded Gaza Strip and killed 1,400 people, mostly civilians, including children, the elderly and revelers at a music festival, and took more than 220 hostages in the deadliest attack in Israel's history.

Israel has struck back with a relentless bombing campaign which Gaza's Hamas-run health ministry says has killed 7,326 people, mostly civilians, among them 3,038 children.

UN Secretary-General Antonio Guterres, meeting Friday with Amir-Abdollahian, urged Iran to work toward the "unconditional and immediate release of hostages held in Gaza."