The Israeli army confirmed carrying out the two missile strikes.
Haim Ramon, Israel's vice president, told Israeli army radio: "If the Qassam [rocket] fire on Israel does not stop, Israel will continue with its pressure on Gaza.
"It is illogical for a country that is attacked by rockets to supply the attacker with power, fuel and water," he said.
On Monday, Benjamin Netanyahu, Israel's opposition leader, called for tougher action against the Gaza Strip to stop rocket fire and remove Hamas from power.
"In a war of attrition the enemy strikes and you react, the enemy strikes harder and you retaliate harder," the former prime minister said in a speech at the 2008 Herzliya conference in Jerusalem.
"This gradual increase in violence is the antithesis of deterrence. Deterrence always means using disproportionate force," Netanyahu said.
"We need to move from a concept of attrition to one of tough deterrence that will eventually lead to the removal of the Hamas regime, because as long as it exists it will continue arming itself and continue its attacks," he said.
But Benita Ferrero-Waldner, the EU's external relations commissioner, said that recent military strikes in the narrow coastal strip of Palestinian territory would not prevent rocket strikes being launched into Israel.
"I am against this collective punishment of the people of Gaza," she said.
"Only a credible political agreement this year ... can turn Palestinians away from violence," she said.
Hamas officials said that the target was a group of fighters who launched makeshift rockets into southern Israel.
"This gradual increase in violence is the antithesis of deterrence. Deterrence always means using disproportionate force"
Benjamin Netanyahu, Israeli opposition leader
Around 230 Palestinian rockets and mortars have been fired over the border since Tuesday, according to the Israeli military.
At least 36 Gazans have been killed by Israeli fire in the past week.
Israel has closed the Hamas-controlled territory's borders, a move taken, Israel says, in response to Palestinian rocket attacks.
The action has plunged Gaza into darkness and invited a humanitarian crisis due to fuel and electricity shortages for 1.5 million Gazans.
Arye Mekel, the Israeli foreign ministry spokesman, said: "The ball is in their court. If they stop the rockets today, everything would go back to normal."
On Sunday evening, Khaled Meshaal, the exiled political leader of Hamas, urged Arab leaders and Mahmoud Abbas, the Palestinian president, to forget their differences and help the Gaza Strip.
Meshaal, in a live interview with Al Jazeera from Damascus, Syria, said: "Oh Arab leaders, every minute in which a Palestinian dies in Gaza, you are responsible for his blood and soul before God."