"Mindful of the risk of escalation, I appeal for restraint to avoid any acts that could deepen the suffering of the Syrian people," Guterres said in a statement.
"These events underscore my belief that there is no other way to solve the conflict than through a political solution."
The Security Council was set to meet at 11:30 am (1530 GMT), at the request of Bolivia, to hear a briefing from UN political chief Jeffrey Feltman.
"Any country that chooses to defend the atrocities of the Syrian regime will have to do so in full public view, for all the world to hear," Haley said in a statement.
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Russia had also demanded an emergency meeting after angrily denouncing the military action as an "aggression against a sovereign state."
US President Donald Trump yesterday ordered cruise missile strikes on a Syrian air base in response to a chemical weapons attack on a rebel-held town that killed 86 people and shocked the world.
The Security Council failed during a meeting yesterday to agree on terms for an investigation of the suspected sarin gas attack in the town of Khan Sheikhun.
Russia's Deputy Ambassador Vladimir Safronkov yesterday warned of "negative consequences" from the US military action, which he described as a "doubtful, tragic enterprise."
"Look at Iraq, look at Libya," he said, referring to Western interventions that unleashed years of chaos in those countries.
Guterres called on the council to unite and agree on a way forward on Syria.
"For too long, international law has been ignored in the Syrian conflict, and it is our shared duty to uphold international standards of humanity," he said.
"This is a prerequisite to ending the unrelenting suffering of the people of Syria.