WASHINGTON: The White House condemned what it called a "reprehensible" and "intolerable" chemical attack in Syria Tuesday and pinned the blame squarely on Bashar Assad's forces.

White House spokesman Sean Spicer said an "extremely alarmed" President Donald Trump had been briefed extensively on the attack, and suggested it was in the "best interest" of the Syrians for Assad not to lead the country.

"Today's chemical attack in Syria against innocent people, including women and children, is reprehensible," Spicer said, adding that the administration was "confident" in its assessment that Assad was to blame.

Spicer said it was a "political reality" that Assad is in power and there was no "fundamental option of regime change."

But the White House comments signaled a tougher tone against the Russian and Iranian-supported regime in Damascus.

"The idea that someone would use chemical weapons on their own people, including women and children, is not something that any civilized nation should sit back and accept or tolerate," he said.

"I think it's in the best interest of the Syrian people to not have anybody who would do the kind of heinous acts," said Spicer.

"Any leader who treats their people with this kind of activity, death and destruction. Yeah. I don't think anyone would wish this upon anybody."

The suspected chemical attack on the rebel-held town of Khan Sheikhun in Syria's northwest Idlib province has left at least 58 civilians dead, including 11 children, according to the Syrian Observatory for Human Rights.

The Syrian army has categorically denied involvement.

Spicer refused to speculate on how the U.S. would respond. "I'm not ready to talk about our next step, but we will get there soon."