BEIRUT — Iran on Thursday accused Israel of conducting a drone attack over the weekend on a Defense Ministry complex in the city of Isfahan. The facility took slight damage, by Iran's account.

"Early investigations suggest that the Israeli regime was responsible for this attempted act of aggression," reads a letter published by Iran's mission to the United Nations. Iran has accused Israel of such attacks in the past.

During a CNN interview Tuesday, Israeli Prime Minister Benjamin Netanyahu refused to confirm or deny whether Israel had targeted the complex. "I never talk about specific operations," he said, "and every time some explosion takes place in the Middle East, Israel is blamed or given responsibility — sometimes we are, sometimes we're not."

Iran's letter, signed by Ambassador Amir Saeid Iravani, did not provide details about the investigation or its findings, but said that a Defense Ministry workshop complex was targeted by three "micro aerial vehicles," two of which were intercepted.

The site probably held sensitive information related to Iran's nuclear technologies and weapons program, said Farzin Nadimi, an Iran analyst at the Washington Institute, a think thank.

These attacks aim to send "a message to the regime in Tehran" that Israel has "access to their sensitive sites and that their air defenses are not impenetrable," Nadimi said earlier this week. A research center affiliated with Iran's civilian space program sits across the road from the complex, which Nadimi said is "very active in supporting the military and Islamic Revolutionary Guard Corps."

The Israel Defense Forces declined to provide comment on the attack. Since the collapse of the 2015 nuclear deal between Tehran and world powers, Israel has conducted attacks on Iranian nuclear program facilities and other sites as part of an ongoing shadow war. The campaign has intensified after Washington withdrew from the nuclear deal in 2018.

Iran's letter demanded the U.N. Security Council bear responsibility to condemn "Israel's warmongering statements and acts of terrorism" and its use of force against "critical infrastructure and peaceful nuclear facilities." It also emphasized its right to defend its national security and respond "wherever and whenever deemed necessary."

The Washington Post's Shira Rubin and Miriam Berger in Jerusalem contributed to this report.