Israeli aircraft struck Hamas positions in Gaza early Wednesday, the military said, after Palestinians in the enclave launched projectiles and explosive balloons at the Jewish state.

In a further punitive move, Israel later restricted Gaza fishing activity, a frequently used sanction against the coastal Palestinian territory. The "fighter jets targeted Hamas terror targets in the southern Gaza Strip" including "a weapons manufacturing site", the army said in a statement.

There were no immediate reports from Gaza of casualties. Prior to the Israeli strike, militants in Gaza launched three projectiles and a number of "explosive balloons" at southern Israel, the army said, with neither medics nor police reporting casualties or damage.

COGAT, a unit of Israel's defence ministry, said in a statement Wednesday that in response it was reducing the permitted Gaza fishing zone from 4pm (1400 GMT) until further notice. "Following security consultations, it has been decided today to restrict the fishing zone of the Gaza Strip from 15 nautical miles to ten nautical miles," the English-language statement said. "The decision was made following the continuity of rocket fire and the launching of explosive balloons from the Gaza Strip to the territory of the State of Israel."

Israel imposed the same restriction in December, also due to rocket fire. It was lifted a few days later. Since US President Donald Trump's announcement last week of his plan to resolve the Israeli-Palestinian conflict, rockets, mortar shells and explosive balloons have been launched almost daily from Gaza into southern Israel, provoking Israeli retaliation.

Palestinians strongly reject the US plan, seen as heavily favouring Israel. Hamas and Israel have fought three wars since 2008 but over the past year the Islamists have gradually shaped an informal truce with Israel, under which the Jewish state has eased its crippling blockade of Gaza.