Lebanon and Israel, still technically at war, held an initial round of negotiations on their disputed maritime border under UN and US auspices on October 14.
The talks resuming on Wednesday are a rare official interaction between countries with no diplomatic ties.
Both sides insist they are narrowly focused on resolving the maritime dispute to allow for oil and gas exploration and do not mark a step towards normalisation.
During a tour of northern Israel, Gantz said: "I am hearing positive voices coming out of Lebanon, who are even talking about peace with Israel, who are working with us on things like determining maritime borders."
Gantz, also Israel's alternate prime minister, did not specify which Lebanese comments he was referring to.
But they came a day after Claudine Aoun, daughter of Lebanese President Michel Aoun, told Al Jadeed TV that peace with Israel would be conceivable if issues between the countries were resolved.
"We have the maritime border dispute, the issue of Palestinian refugees, and another topic which is more important which is the issue of natural resources: water, oil and natural gas which Lebanon is depending on to advance its economy," she said.
When asked directly if she would object to a peace treaty with Israel, she responded: "why would I object?"
"Are we supposed to stay in a state of war?... I don't have doctrinal differences with anyone... I have political differences."
The Shia group Hezbollah, a major force in Lebanese politics, has criticised the maritime talks.
Israel and Hezbollah last fought a war in 2006, but the sides still exchange sporadic cross-border fire.
Gantz's comments came with Israel deepening its Arab ties through a series of US-brokered deals.
The United Arab Emirates and Bahrain have established diplomatic relations with the Jewish state, breaking decades of Arab League consensus against normalisation with Israel until the Palestinian conflict is resolved.
Sudan has said it also intends to establish full diplomatic relations with Israel.
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