Israel launched airstrikes against Gaza on Monday, the army and a source inside the enclave said, after incendiary balloons launched from the strip started fires in the country's south.
The latest escalation of tension follows weekend border clashes in which dozens were injured.
There were no casualties in the raids on Gaza City, Khan Younes in the south, and Jabalia in the north, but they did cause material damage, the Palestinian security source said, speaking on condition of anonymity.
He added that fighters loyal to the ruling Hamas Islamist movement had fired on the Israeli aircraft.
In a statement, the Israeli Defence Forces (IDF) confirmed that fighter jets attacked "a Hamas weapons manufacturing site in Khan Yunis as well as terror tunnel entrance in Jabalia".
"A Hamas underground rocket launch site that is located adjacent to civilian homes and a school in Shejaiya was also struck," it added, saying "the strikes were in response to Hamas launching incendiary balloons into Israeli territory".
Israel frequently responds to incendiary balloon launches with airstrikes, including after such devices were used on August 6.
They are a common tactic used by Palestinian militants in the Gaza Strip, which has been under a strict Israeli blockade since 2007, when Hamas took power there.
In a statement earlier on Monday, the fire service said it was working to contain a number of fires in the Eshkol border region, which it blamed on at least nine incendiary balloons launched from Gaza.
Saturday saw intense hostilities on the border.
Israeli troops fired at Palestinian protesters who had gathered near the Gaza border and hurled explosives and tried to scale the wall.
An Israeli border police officer and a 13-year-old Palestinian were critically injured.
The escalation came exactly three months since Israel and Hamas reached a truce following their deadliest fighting in years.
Over 11 days in May, Israel pounded Gaza with airstrikes in response to rockets fired from the enclave.
Israeli strikes killed 260 Palestinians, including fighters, while munitions fired by militants in the territory killed 13 people in Israel, including a soldier.
