Most of them caused no injuries or damage but two struck the southern coastal town of Ashdod on Friday morning, damaging a school and a synagogue and seriously wounding one person, Israeli police and the military said.
The uptick in rocket attacks came as Israeli fighter jets staged seven overnight air strikes on targets across Gaza which killed a teenager and injured 17 people, Palestinian medics said.
The Israeli strikes were launched just hours after a series of deadly attacks near the Red Sea resort town of Eilat, which killed eight Israelis in an operation Israel blamed on the Gaza-based Popular Resistance Committees (PRC).
Shortly after the attacks on a desert road, Israel attacked targets in southern Gaza, killing six -- including four top PRC militants and a two-year-old boy.
The group vowed bitter revenge and on Friday claimed responsibility for firing two Grad rockets toward the port city of Ashkelon and seven mortars at an army post near the southernmost point of the Israel-Gaza border, close to Egypt.
On Friday, the military wing of the Popular Front for the Liberation of Palestine also vowed that Israel's attacks would not pass without "punishment and revenge."
The Abu Ali Mustapha brigades called for unity and resolve in the face of the attacks in a statement received by Ma'an.
Overnight, the Israeli air force staged seven raids, hitting two training camps for the armed wing of Hamas, the Al-Qassam Brigades, as well as Palestinian security posts, medics said.
The Israeli military confirmed the raids, saying it had targeted a weapons manufacturing site, two smuggling tunnels, a "terror tunnel" and several other sites in the wake of the desert attacks and the rocket fire on southern Israel.
"The Israeli Defense Forces will not tolerate any malicious attempt to harm Israeli civilians and IDF soldiers, and will not hesitate to respond with strength and determination to any element that uses terror against the State of Israel and until calm is restored," it said in a statement.
It also blamed the bloodshed on Gaza's Hamas rulers, who had on Thursday denied any connection to the coordinated attacks near Eilat.
"The IDF holds the Hamas terrorist organisation solely responsible for any terrorist activity emanating from the Gaza Strip."
Egypt's official MENA news agency reported, meanwhile, that two Egyptian policemen were killed on Thursday when an Israeli plane fired a rocket near the border at militants it was tracking after the deadly desert attacks.
The incident took place near the Rafah border crossing with Gaza, the agency quoted a military official as saying.
"An Israeli plane was pursuing infiltrators on the other side of the border until they reached Rafah and fired at them. There were several Central Security members there and they were hit by the gunfire," the official told MENA.
State television reported that the two police conscripts were killed southwards from Rafah near Taba, roughly 12 kilometers from the Israel town of Eilat close to the site of the attacks.
The Israeli military has not immediately commented on the reports.
Maan News Agency