Perhaps they want Hezbollah weakened?

https://www.csis.org/analysis/israel-hezbollah-escalation

The U.S. government is deeply sympathetic to Israeli efforts to weaken Hezbollah. Hezbollah is a foreign terrorist organization, and the U.S. government doesn’t talk to Hezbollah. As mentioned previously, Hezbollah is a militia that operates with impunity from the rules of the state of Lebanon. From the perspective of the U.S. government, diminishing Hezbollah’s capabilities is not a bad thing. Rather, the United States’ challenge is ensuring that this escalation does not tip the entire region into war. The region is a tinderbox. There are already issues of increasing violence in the West Bank, there’s a war in Gaza, and Iran is certainly involved in many regional activities, including Houthi threats to navigation in the Red Sea.

While the Biden administration is concerned that things could get out of control, there is also a broader context. When Israel has taken military action in the past, the U.S. government has often waited a couple of weeks before trying to roll things back. This week, the president is preoccupied with his address to the UN General Assembly. There’s a sense that Israel is still doing necessary—and perhaps from the view of some members of the U.S. government—useful work by knocking Hezbollah back. If the escalation stays within manageable parameters, the United States will likely try to apply pressure on Israel in the next week. From an Israeli perspective, they can act with relative impunity this week. After the pager attack, Hezbollah doesn’t trust its communication systems and doesn’t seem to be pressing toward war. From an Israeli perspective, Iran doesn’t seem to be pressing toward war either, which makes it less risky for Israel to act strongly against Hezbollah. Looking toward the weekend, there will likely be a continued escalation in Israeli actions, although it is unlikely that the situation will tip into an all-out war before then.