Prime Minister Benjamin Netanyahu fired Yoav Gallant on Tuesday after frequent clashes over Israel's retaliatory military offensive against Hamas following the Palestinian militant group's deadly attack on Israel on October 7 last year.

Before taking over from Gallant, Katz -- who vowed to defeat Israel's enemies -- was the foreign minister, with Gideon Saar appointed successor.

Katz's last day as foreign minister was marred by a diplomatic incident with France, when Israeli police entered a French-owned church compound in Jerusalem and briefly detained two gendarmes.

The incident prompted French Foreign Minister Jean-Noel Barrot to abandon a scheduled visit to the site, the Eleona church compound in annexed east Jerusalem.

Speaking alongside Katz on Thursday, Barrot said "Israel has the right to defend itself" but pointed to "colonisation", "humanitarian aid restrictions" and "the continuation of air strikes in north Gaza" as risk factors for Israel's security.

Opposition leaders from across Israel's political spectrum blasted Netanyahu's decision to fire the defence minister in the midst of war and thousands of Israelis took to the streets to protest.

Gallant and Netanyahu had notably disagreed on the issue of exemption from military service for ultra-Orthodox men.

The sacked minister had been a key advocate for ultra-Orthodox Jews to be called up, but Netanyahu wanted their exemption to continue, fearing their conscription could break up his far-right coalition government.