By Rami Ayyub and Nidal al-Mughrabi

Israeli aircraft bombed a Hamas site in the Gaza Strip overnight in response to incendiary balloons launched from the Palestinian enclave, Israel's military said on Friday.

There were no immediate reports of casualties from the Israeli strikes, which the military said targeted a weapons manufacturing site used by Hamas, Gaza's Islamist rulers.

Since a May 21 ceasefire ended 11 days of Israel-Hamas fighting, Palestinians in Gaza have sporadically launched balloons laden with incendiary material across the border, causing fires that have burned fields in Israel.

Palestinians say the balloons aim to pressure Israel to ease restrictions on the coastal enclave that were tightened during the May fighting.

Balloon launches had ebbed after Israel eased some restrictions on Gaza last week. But on Thursday, balloons were again launched from Gaza, causing at least four brush fires near Israeli cities along the border.

"In response to the arson balloon fire towards Israeli territory today IDF (Israeli military) fighter jets struck (a) weapons manufacturing site belonging (to) Hamas," the military said in a statement.

There was no immediate comment from Hamas.

Egypt and the United Nations have stepped up mediation efforts over the Israeli strikes and Gaza balloon launches, though the incidents have not led to a broader escalation.

At least 250 Palestinians and 13 in Israel were killed in the May fighting, which saw Gaza militants fire rockets towards Israeli cities and Israel carry out air strikes across the coastal enclave.