Plumes of smokes were seen rising above Gaza City after Israeli strikes
The attacks come after a major rocket barrage on Israel launched from south Lebanon, which the Israelis blamed on Palestinian militant group Hamas.
The Israel Defense Forces (IDF) said Hamas' "terrorist" infrastructure was hit in southern Lebanon.
Tensions are high after Israeli police raided Jerusalem's Al-Aqsa mosque on consecutive nights earlier this week.
Hamas said it had no information about who fired the missiles from Lebanon. The attack was the biggest single barrage from Israel's northern neighbour in 17 years.
Hamas chief Ismail Haniyeh, who was in Lebanon when the rockets were launched, said Palestinians would not "sit with their arms crossed" in the face of Israeli aggression.
In a statement early on Friday, the IDF said it had truck targets "including terrorist infrastructures belonging to Hamas in southern Lebanon".
The IDF added that it would not allow Hamas to operate from Lebanon and held Lebanon "responsible for every directed fire emanating from its territory".
Israeli warplanes also stepped up air strikes in Gaza, with around 20 missiles striking four new sites in 10 minutes. Palestinian militants also fired a new round of rockets at southern Israel.
The airstrikes are said to be the heaviest since a round of fighting with Islamic Jihad in August 2022.
--- Courtesy of BBC News