"I'm not going to speak to that except to say that the United States has not been involved in any offensive operations," Blinken said at a news conference on Friday capping a gathering of G7 foreign ministers on the southern Italian island of Capri.
"What we're focused on, what the G7 is focused on, and again, it's reflected in our statement, and in our conversation, is our work to de-escalate tensions, to de-escalate from any potential conflicts."
The top US diplomat kept repeating the same response, almost verbatim, when he was asked about the issue several times at the news conference.
At a separate news conference moments before Blinken, Italy's Foreign Minister Antonio Tajani said the United States was "informed at the last minute" but did not elaborate.
Explosions echoed over the Iranian city of Isfahan in the early hours of Friday in what sources described as an Israeli attack, but Tehran played down the incident and indicated it had no plans for retaliation - a response that appeared gauged towards averting region-wide war.
Israel said nothing about the incident.
It had said for days it was planning to retaliate against Iran for Saturday's strikes, the first direct attack on Israel by Iran in decades of shadow war waged by proxies which has escalated throughout the Middle East during six months of battle in Gaza.
