US officials first warned Qatar around 10 minutes after the Israeli attack on Tuesday began, Qatari Prime Minister Mohammed bin Abdulrahman told reporters.
An Israeli strike on the leadership of the Palestinian organization Hamas in Doha killed six people.
"The US side informed us 10 minutes after the attack happened that they've just received a message that there is an attack, a missile fired, at the State of Qatar," he said.
When asked about the Gulf country's air defences Mohammed, who is also the foreign minister, said "the Israeli enemy used weapons that were not detected" by the system.
He described the attack as "a 100% treacherous operation" and "state terrorism."
Qatar, alongside Egypt and the United States, has been mediating in the Gaza war between Israel and Hamas, though ceasefire negotiations have been stalled for months.
He vowed that Qatar will maintain its mediator role, despite the attack.
"Qatar has spared no effort to stop this war and will do whatever it can to stop this war, to stop this hostility on Gaza," he said.
Mediation "will continue, and nothing will deter us from continuing this role," the prime minister added.
