The pope said the attacks, in which Israel says it has been striking targets affiliated with the Iran-backed Hezbollah movement, were "unacceptable" and urged the international community to do everything possible to halt the fighting.
Francis did not specifically identify Israel, but said he was "saddened by news from Lebanon in recent days that bombardments have caused much destruction and many victims".
The 87-year-old pontiff, who has suffered bouts of ill health in recent years, appeared in good form through his audience although he coughed lightly a few times while speaking.
The Vatican has not provided details about the pope's health since announcing on Monday he had cancelled his meetings for that day. It said at the time the pontiff had made the decision as a precautionary measure in view of a trip to Luxembourg and Belgium, which starts on Thursday.
At the audience, the pope confirmed his plans to continue with the visit, and asked for prayers for its success.
The tour, his 46th foreign visit as pope, comes less than two weeks after he returned from a demanding 12-day, four-country excursion around Southeast Asia and Oceania.
The pope referred to the strikes in Lebanon in off-the-cuff remarks at the end of his hour-long audience.
Francis, pope since March 2013, now regularly uses a wheelchair due to knee and back pain. Earlier this year, he cancelled several appointments over what the Vatican variously described as a cold, bronchitis and influenza.
On the Sept. 2-13 trip to Indonesia, Papua New Guinea, East Timor and Singapore, Francis maintained a packed schedule, headlining more than 40 events, and travelling some 33,000 km (20,500 miles).
Francis started the general audience on Wednesday by taking a tour around the crowd in an open-air popemobile, waving to people as a band played orchestral versions of pop songs.
In his main messages to pilgrims, the pope focused on the dangers of temptation, including online pornography, which Catholic teaching forbids.
