Israel launched more airstrikes Monday in the Gaza Strip, targeting what its military said was a tunnel network used by Hamas, as it tries to blunt the militant group’s ability to attack Israeli territory.

The two sides continued to trade fire despite international calls to bring the fighting to an end after 42 Palestinians died Sunday, the deadliest day of the current escalation.

The Israeli military said assaults with warplanes hit roughly 60 miles of underground passageways that it says are used to ferry weapons and fighters across Gaza, a subterranean network Israel has dubbed Hamas’s metro. The military also said it thwarted a potential Hamas underwater attack into Israeli territory with a submerged vessel and killed a senior commander with the Gaza militant group Palestinian Islamic Jihad, which confirmed the killing. Israeli forces later destroyed a large building in the Rimal neighborhood it said was the main operations center for Hamas’s internal security services.

Yahya al-Sarraj, the mayor of Gaza City, the strip’s biggest population center, said the strikes hadn’t targeted military positions and instead hit roads and civil infrastructure, setting the economy back years. He called the strikes collective punishment and asked the international community to stop assaults on vital infrastructure in Gaza.

Hamas, which rules Gaza, also fired scores of rockets toward Israel overnight and Monday, causing light injuries, the Israeli military said.

Prime Minister Benjamin Netanyahu has said Israel would continue to strike positions in Gaza until it has degraded Hamas’s military capabilities and hurt its capacity to wage attacks against Israelis, adding that the military campaign will take time. Mr. Netanyahu has described Hamas’s decision to launch rockets toward Jerusalem a week ago as a red line.

“We are going to continue hitting targets in Gaza,” Mr. Netanyahu said late Monday. “We will continue to act as much as needed to restore calm.”

Inside Israel, violence between Israeli Jews and Arabs that racked the country in recent days appeared to be dissipating Monday, Israeli officials said. The Israeli police said they had responded to more than 40,000 incidents and carried out over 900 arrests over the past week.