Israel bombed positions of Al-Quds Brigades, the military wing of the Palestinian group Islamic Jihad, early Friday in the cities of Khan Younis and Rafah in the southern Gaza Strip.
No casualties have been reported so far. They had claimed that two rockets had been launched from Gaza a few hours ago.
The Israeli army announced the operation on its Twitter account.
A truce was reached in Gaza that went into effect on Thursday at 5 a.m. local time, but a lasting ceasefire appeared tenuous due to differences over its terms.
On the other hand, hundreds of Palestinians carrying black Islamic Jihad flags gathered at Al-Mujahideen Mosque in central Gaza on Thursday to attend funeral prayers for eight members of the Abu Malhous family.
The eight family members were killed by Israeli air raids in the early hours of Thursday in Deir al-Balah. They were among 34 Palestinians killed by Israeli air raids over the Gaza Strip during two days of cross-border fighting between Israel and the Islamic Jihad.
At least 63 Israelis also received treatment for injuries from rocket fire from Gaza.