U.S. President Joe Biden delivered a stern, one-word warning to Iran on Friday as the world braced for Tehran to exact revenge for a deadly Israeli airstrike on its embassy compound in Damascus, Syria.

“Don’t,” Biden said to reporters following a speech on domestic policy at an event in New York City.

“We are devoted to the defense of Israel,” the president said in response to questions from reporters. “We will support Israel. We will help defend Israel, and Iran will not succeed."

Biden’s comments followed similar expressions of support from top U.S. defense and diplomatic officials over the past several days and come as the U.S. military takes steps to ensure growing hostilities between Israel and Iran do not engulf the Middle East in a wider war.

"We are moving additional assets to the region to bolster regional deterrence efforts and increase protection for U.S. forces," a U.S. defense official told VOA Friday. The official, who spoke on the condition of anonymity, declined to share additional details.

Even as U.S. officials warned Iran against seeking revenge, a key Iranian proxy sprang into action.

Lebanese Hezbollah late Friday fired dozens of rockets into the northern part of the country.

The Israel Defense Forces said it detected about 40 rockets crossing from Lebanon into Israel, some of which were intercepted by air defense systems.

The IDF also said it was able to intercept two explosive drones that Hezbollah militants had used to target Israel earlier Friday.

It is unclear whether the rocket and drone attacks by Hezbollah were part of an effort by Iran to retaliate for the Israeli strike on Iran’s diplomatic compound earlier this month, which killed three senior Islamic Revolutionary Guard Corps commanders, including General Ali Reza Zahdi, who led Iran’s elite Quds force.