"We warn them of a large volcano that will erupt if their aggression increases."
Almost 29 rockets were fired towards southern Israel on Friday, Israel's army said.
Two buildings were hit, including a house, Israeli media reported and two people were reported injured, according to medics.
The rocket attacks came despite Israeli action on Thursday to carry out further power cuts.
Israel normally supplies 60 per cent of the electricity for Gaza's 1.5 million inhabitants
Gaza needs around 240 megawatt of electricity, but normally receives only about 200 megawatts, with 8 per cent from Egypt
Israel is the only source of industrial fuel for Gaza's power station
Israel stopped supplying industrial fuel supplies to Gaza on January 19
The EU pays Israel around $10m per month for Gaza's industrial fuel
Israel curbed about one per cent of the power it supplies to Gaza, Israel's defence ministry said. It was the latest of several Israeli measures meant to pressure Hamas.
Since Hamas took control of the Gaza Strip in June, Israel has imposed a virtual blockade of the territory, reduced fuel supplies and launched air raids and ground operations against Palestinian fighters.
In Israeli attacks this week, 17 Palestinians have been killed.
Shlomo Dror, an Israeli ministry spokesman, said on Friday that Israel will continue cutting back Gaza's electricity supplies until Hamas ends the rocket fire.
"It's their choice. They need to choose if they want to keep investing in rockets and in attacking Israel or if they want electricity from Israel," Dror said.
Tensions sparked earlier this week when Hamas took responsibility for a suicide bombing in southern Israel on Monday in which one woman was killed and 11 others wounded.
It was the first such attack by Hamas in three years.
Human rights groups have complained that measures like cutting back on fuel and power are collective punishment, harming civilians.
The ongoing violence threatens to hamper US-backed plans by Israel and the government of Mahmoud Abbas, the Palestinian president, to reach a peace agreement by the end of the year.
Israeli leaders have said the Gaza rocket fire must factor into peace negotiations which resumed at a conference in November.
Israel withdrew from the Gaza Strip in 2005 after 38 years of occupation, but still controls all its passages to the world except the one with Egypt.