The exchange came hours after two Palestinian teenagers were killed by Israeli fire during clashes on the Gaza border. (AFP)

Israeli warplanes attacked an arms plant in the Hamas-controlled Gaza Strip early Thursday, after Palestinian militants in the enclave fired a rocket at Israel,the army said.

“Overnight, a rocket was launched from the Gaza Strip at Israeli territory,” an English-language army statement said.

“In response… fighter jets struck a Hamas weapons manufacturing site in the northern Gaza Strip.”

There were no immediate reports of casualties in the overnight rocket attack or the air strike that followed.

Later on Thursday, Israeli authorities announced a punitive reduction in the fishing zone off Gaza.

COGAT, a unit of Israel’s defence ministry, said that in response to the latest rocket fire, “the Gaza Strip fishing zone has been reduced to 10 nautical miles until further notice.”

Israel constantly adjusts the fishing zone according to the level of tension around Gaza, sometimes allowing boats to fish up to 15 nautical miles offshore and at others restricting them to six or banning fishing altogether.

Hamas has controlled Gaza since 2007, and Israel generally holds the Islamist movement responsible for all rocket fire coming from the territory, although it has targeted other militant groups too.

On Tuesday, an Israeli aircraft hit what the military said was an armed Palestinian seen approaching the Israeli border fence in Gaza.

His death has so far not been officially confirmed as no body has been retrieved from the no-go area adjacent to the frontier.

Last month, Israeli forces assassinated a senior Islamic Jihad leader in the Gaza Strip, sparking a two-day flare-up which killed 36 Palestinians.

Islamic Jihad fired around 450 rockets at Israel, many of which were intercepted by the Iron Dome defence system.

Israel has fought three wars with Hamas and allied armed groups in Gaza since 2008.