A broader regional war in the Middle East where conflict already rages between Hamas and Israel remains a "significant risk," the head of the U.N. peacekeeping force warned.

Speaking to reporters in Brussels, United Nations Under-Secretary-General for Peace Operations Jean-Pierre Lacroix warned against making assumptions about how regional actors will behave.

"The perception could exist that there are certain rules that neither parties want to trespass and therefore that we are in a situation that is more stable than one could think," Lacroix said on the sidelines of an EU defense ministers' meeting.

"There is still a very significant risk of escalation at the regional level," he said, adding: "We are still very much in a very, very dangerous type of situation."

Tensions have risen since the October start of Israel's war in Gaza, with Hezbollah supporting the Palestinian armed group Hamas with operations in southern Lebanon, including daily exchanges of fire with Israeli troops.

Hundreds of Hezbollah fighters have been killed in cross-border fighting, while around 100,000 people on both sides of the border have been displaced.

Lacroix warned of the risk of an "unintended" escalation or a "misunderstanding."

"One of the risks, in particular in southern Lebanon, is both parties not exactly understanding where the other is in terms of calculus," he said.

On Sunday, Hezbollah carried out a major drone and rocket attack against Israel, in retaliation for the death of one of its military leaders, Fouad Shukur, killed in an Israeli strike near Beirut on July 30.

In response, Israel launched air strikes into Lebanon the same day.

Amid escalating tensions, the U.N. Security Council extended the mandate of the U.N. peacekeeping force in Lebanon -- numbering around 10,000 -- for a year.

The war in Gaza erupted after Hamas-led militants attacked Israel on October 7, resulting in the deaths of hundreds of Israelis. Israel's retaliatory military campaign has killed at least 40,602 people in Gaza.

Israel this week also pressed a large-scale military operation in the occupied West Bank, despite U.N. concerns it is "fueling an already explosive situation."