In Lebanon, there is little appetite for war, as the country suffers through a crippling economic crisis. Regionally, if Hezbollah opened a second front, it could prompt the United States to come to Israel’s aid.

“All of Lebanon, including Hezbollah — we don’t want a war,” said Lebanon’s foreign minister, Abdallah Bou Habib, who is in regular contact with Hezbollah. “There is Western pressure on the Lebanese government to apply pressure on Hezbollah not to go to war. We have dialogued with Hezbollah and my impression is that they won’t start a war. But will Israel start a war? We need equal pressure on them, too.”

American officials have privately urged Israeli leaders not to launch a major strike on Hezbollah that could plunge the region into all-out bloodshed.

“We don’t seek an escalation in the north,” Ron Dermer, Israel’s minister of strategic affairs, said at a news conference on Monday. “Hezbollah may decide they’re going to escalate, and we’re going to have to respond and we’re prepared for that.”

“We hope they don’t make that mistake,” Mr. Dermer added. “They made a mistake, I think, in 2006. I think the leader of Hezbollah said if he knew what the response was going to be, he never would have started it. Believe me, the response now will make what happened in 2006 look like child’s play.”

But, Mr. Bou Habib said, if the carnage in Gaza worsens, or Israel escalates its attacks in Lebanon, Hezbollah may feel more pressure to respond.

“If the situation gets really bad in Gaza, it will be really bad for the whole region — not just Lebanon and Israel,” Mr. Bou Habib said.

Hezbollah, like Hamas, has been designated a terrorist organization by the United States and other countries.

Some Hamas leaders have suggested that they expect more help from Hezbollah.

Khaled Meshaal, the political leader of Hamas until 2017, said that the group’s regional allies could contribute more to the war effort.

“When such a heinous crime is perpetrated against Gaza, greater things are certainly needed,” Mr. Meshaal said in a recent interview with Al Arabiya, a news channel. “But we should not single out Lebanon and Hezbollah.”

While Hezbollah’s precise capabilities remain unclear, it can clearly cause damage inside of Israel. The group is believed to have an arsenal of up to 150,000 rockets, as well as precision guided missiles capable of striking sensitive targets.

“Hezbollah today is in a position to inflict pain on Israel if they choose to enter this war,” said Maha Yahya, the director of the Carnegie Middle East Center in Beirut.

“The range of response Hezbollah can have is pretty versatile,” Ms. Yahya said. “They don’t need to do a ground incursion into Israel. With Iran, they could start using the Syrian front and there could be attacks outside of Israel, not necessarily inside Israel against Israeli interests. That has happened before.”

The Hezbollah leader Hassan Nasrallah has been unusually quiet since the Oct. 7 attacks that Hamas launched into Israel, killing some 1,400 people, mostly civilians, and taking more than 230 civilians and soldiers hostage. Israel has responded with a vast bombing campaign on Gaza, a blockade on fuel and a ground invasion. Mr. Nasrallah is scheduled to address his followers on Friday, leaving the region on edge.