An Israeli military official said "an explosion was detonated" on Wednesday when the soldiers entered a site in the village of Majdal Zoun and that the nature of the explosive was under review.
A precarious truce between Israel and Hezbollah has largely held since June 20, but Israeli forces have continued to occupy swathes of southern Lebanon and to carry out periodic air strikes and shelling.
The latest escalation came as Lebanese and Israeli negotiators met in Rome to discuss implementation of a June 26 deal reached between Israel and the Lebanese government under which Israeli forces are supposed to withdraw from areas they occupy in southern Lebanon and allow the Lebanese army to take control, in exchange for Hezbollah's disarmament.
Hezbollah has refused to disarm and opposed the direct Lebanon-Israel talks. It was not a party to the deal.
The group has accused the Lebanese government of making too many concessions without guaranteeing an Israeli withdrawal.
Wednesday's talks ended early due to the escalation on the ground, but were set to resume on Thursday.
The talks in Rome have focused on implementation of "pilot zones" where Israeli forces would withdraw and the Lebanese army would take control. Implementation began in July with an initial pilot zone in an area that wasn't occupied by Israeli forces but had previously sustained Israeli fire.
The Lebanese army entered the town of Zawtar al-Gharbieh and some civilians returned, although many came only to find their homes destroyed and left again.
The Israeli army launched strikes on Wednesday in southern Lebanon in response to what it described as Hezbollah's violation of the ceasefire and called on residents of the village of Mansouri to flee - the first such warning Israel has issued in Lebanon for weeks.
Lebanon's health ministry said one person was killed and 12 wounded in an Israeli strike in the town of Tebnine on Wednesday and another eight wounded in overnight strikes on the village of Burj al-Shemali.
Artillery shelling also targeted the areas of Mansouri and Majdal Zoun, the state-run National News Agency said.
There was no immediate statement from the Iran-backed Hezbollah.
The latest Israel-Hezbollah war erupted on March 2, when Hezbollah fired rockets across the border two days after the US and Israel launched their attacks on Iran.
More than 4000 people have been killed by Israeli strikes in Lebanon since then, including hundreds of civilians.
About 40 soldiers and three civilians - including a military contractor - have been killed on the Israeli side.
