Israel says its missile defenses have intercepted two rockets fired from the Gaza Strip.
The firings early Saturday raise more doubts about the fate of a fragile cease-fire that was announced Thursday.
The Egyptian-brokered lull ended two days of escalation between Israel and the Islamic Jihad.
A rare Israeli targeted killing of a senior commander from the Iranian-backed group triggered the worst bout of cross-border fighting in years.
Hamas, the larger Islamic group controlling Gaza, stayed on the sideline, fearing its participation could cause an all-out war.
The Islamic Jihad said it launched hundreds of rockets toward Israel in retaliation for the killing of the commander Bahaa Abu el-Atta.
Subsequent Israeli airstrikes killed 34 Palestinians, including eight children and three women. There were no Israeli deaths.
