Israeli President Shimon Peres briefed U.S. President Barack Obama on Wednesday about Israel's killing of the Hamas military commander in Gaza, saying the man was a "mass-murderer", Peres's office said in a statement.
Peres, a Nobel Peace Prize laureate and former Israeli prime minister, told Obama that the killing of Hamas's Ahmed al-Jaabari was Israel's response to a surge in cross-border Palestinian rocket and mortar salvoes from Gaza.
"Israel is not interested in stoking the flames, but for the past five days there has been constant missile fire at Israel and mothers and children cannot sleep quietly at night," Peres was quoted as telling Obama.
"There is a limit to what Israel can absorb," said Peres, who visited the Israeli border town of Sderot on Wednesday.
The Obama administration responded to the flareup by strongly condemning Hamas, an Islamist group shunned by the West as an obstacle to peace.
"There is no justification for the violence that Hamas and other terrorist organizations are employing against the people of Israel," said Mark Toner, deputy U.S. State Department spokesman.
"We call on those responsible to stop these cowardly acts immediately. We support Israel's right to defend itself, and we encourage Israel to continue to take every effort to avoid civilian casualties."
Israel's air strikes killed 10 people, including Jaabari and at least five civilians, on Wednesday, Palestinian doctor said.
Israeli Prime Minister Benjamin Netanyahu's office said he spoke separately with Obama and "voiced deep appreciation for (his) support of Israel's right to defend itself".
As a presidential candidate in 2008, Obama came to Sderot and voiced sympathy with residents under threat of rocket attack from nearby Gaza.
He raised that visit during his successful campaign for re-election this month, after being accused by Republican rival Mitt Romney of being soft on Israel's security.