Iranian leaders have vowed to punish Israel for killing top Iranian commanders this week in an airstrike in Syria. The attack was one of the deadliest in a decades-long shadow war between the two enemies, and American officials have voiced concerns that it could prompt retaliatory strikes against Israel or the United States.

Israel said on Wednesday night that it had decided to mobilize reserve soldiers for its Aerial Defense unit. On Thursday, it said it was pausing leave for all combat units given “the latest situational assessment.”

Rear Adm. Daniel Hagari, a military spokesman, said Israel had also been disrupting GPS signals to intercept any threats.

“During the war, we dealt with a large number of threats launched toward Israel” including missiles and drones, he said at a news briefing on Thursday, adding that “most of them were manufactured in Iran.”

As outrage continues to boil over the killing of the aid workers this week, their employer, World Central Kitchen, called for an independent investigation into the attack and asked Australia, Britain, Canada, the United States and Poland, whose citizens were among the victims, to join it in demanding an outside inquiry.

World Central Kitchen also called on Israel to preserve documentation related to the strikes and pushed back on Mr. Netanyahu’s assertion that strikes, while “tragic” and unintentional, were something that “happens in war.”

“This was a military attack that involved multiple strikes and targeted three W.C.K. vehicles,” the statement said. “All three vehicles were carrying civilians; they were marked as W.C.K. vehicles; and their movements were in full compliance with Israeli authorities.”

Reporting was contributed by Lara Jakes, Adam Rasgon, Johnatan Reiss, Eric Schmitt, Mark Landler, Katie Rogers and Michael Levenson.