The US secretary of State Antony Blinken spoke from Tel Aviv after spending a day with Israeli officials.
Mr Blinken met also Israel’s prime minister Benjamin Netanyahu to discuss further boosting of the military support offered to Washington’s closest Middle East ally.
“I understand on a personal level, the harrowing echoes that Hamas’ massacres carry for Israeli Jews, indeed, for Jews everywhere,” he said during a joint press conference.
“There is no excuse. There is no justification for these atrocities,” he added. “This must be a moment for moral clarity.”
The “brutality and inhumanity” of Hamas was similar to “the worst of ISIS,” Mr Blinken added.
At least 1,200 Israelis have died in the attack launched by Hamas and over 1,100 Palestinians have been killed in air strikes on Gaza in recent days.
