Israeli forces attacked Hamas positions in Gaza after rockets fired from the Palestinian enclave hit the Jewish state, the military said early Saturday.
The exchange came hours after two Palestinian teenagers were killed by Israeli fire during clashes on the Gaza border.
Late Friday, "five projectiles were launched from the Gaza Strip towards Israel," the army said.
The projectiles hit open fields in southern Israel, an army spokesman told AFP.
In response, an "aircraft and tank struck a number of Hamas military targets in the northern Gaza Strip, including a post and military positions," the army said in a statement.
A Hamas security source said there were no casualties resulting from the Israeli strikes.
Later Saturday, a drone launched from southern Gaza crossed into Israeli airspace, the army said in a separate statement.
It "dropped what seems to be an explosive device" near the security fence, damaging a military vehicle before returning to Gaza.
In response, an Israeli "aircraft targeted the squad which launched the drone", the army said.
There were no reports of casualties in Gaza, but the unrest on the frontier continued throughout the day as four Palestinians infiltrated Israel and were apprehended by the army.
During border clashes on Friday, two Palestinians aged 14 and 17 were shot dead by Israeli forces, the Gaza health ministry said, with another 46 Palestinians wounded.
Palestinians have been holding regular mass protests along the fortified border since March 2018.
The protesters have called on Israel to end its crippling siege of the coastal enclave and demanded the right to return to lands their families fled during the war that accompanied the creation of Israel in 1948.
Israel says any such return would mean its end as a Jewish state and accuses Gaza's Islamist rulers Hamas of using the protests as cover for attacks.
At least 308 Palestinians have been killed by Israeli fire in Gaza since the protests began, the majority during the demonstrations.
The protests have calmed in recent months.
Israel and Hamas have fought three wars since 2008.