The Israeli military said it has carried out air strikes on four Hamas targets in the Gaza Strip on Thursday in response to what it said were mortar rounds fired into its territory.

The Gaza Health Ministry said three children and a 65-year-old suffered light-to-moderate wounds in a strike that hit a metal workshop in the besieged Palestinian enclave.

The Israeli army said it hit what it called "terrorist infrastructure sites" early on Thursday and the sites belonged to Hamas, which governs Gaza.

Palestinian media said an outpost of the Islamic Jihad group was also targeted.

Israel also said it struck five Hamas targets on Wednesday, in what it said was a response to a mortar shell fired towards its forces near the Gaza.

The army said no soldiers were harmed in those attacks.

Israeli military spokesman Lt Colonel Peter Lerner called it the "most serious" escalation since the 2014 Israeli war on Gaza that killed more than 2,000 people, mostly Palestinians.