Again, link to the article if you're going to cite/discuss its headline, please. Axios names a culprit in the headline because their source isn't just the word of the governments of Iran and Qatar. First line of the article:

The Israeli Air Force struck a natural gas processing facility in southwestern Iran, two senior Israeli officials said.

Followed later by:

Two Israeli and U.S. officials said the strike on the gas facility was coordinated between the Israeli prime minister's office and the White House.

"The U.S. was aware, but was not part of the attack", a third source said.

Insiders taking responsibility for an attack combined with an accusation from the victims is a much stronger green light to name a culprit in the headline.

Edit (incidental): This is what the WSJ is reporting as a live update: more from US officials about the US' support of Israel's attack.

News like this is chaotic, so I appreciate organizations only reporting what they can confirm.