Haley told the Security Council on Monday that there was "obvious evidence from dozens of victims" to corroborate the chlorine attacks in Eastern Ghouta.
"Now we have reports that the Assad regime has used chlorine gas against its people multiple times in recent weeks, including just yesterday," Haley said, referring to the government of Syrian President Bashar al-Assad.
The United States has suggested a draft statement denouncing the use of chemical gases as a weapon but Russia called for the delay of its adoption, according to diplomats.
"Russia has delayed the adoption of this statement - a simple condemnation of Syrian children being suffocated by chlorine gas," she said.
This is despite the fact that US Defense Secretary James Mattis said on Friday that the United States has no evidence to confirm reports that the Syrian government used the chemical nerve agent of sarin against its civilians.
Mattis said that Washington was “concerned” about the use of sarin in Syria but could not confirm reports from NGOs and militant groups regarding the issue.
"We are even more concerned about the possibility of sarin use... I don't have the evidence, what I am saying is, that other groups on the ground … have said that sarin has been used, so we are looking for evidence," the Pentagon chief said.
Sarin is a colorless and tasteless toxin that can cause respiratory failure leading to death.
Accusing the Assad government of using chemical weapons against civilians, the US launched several dozen Tomahawk cruise missiles at a Syrian air base last April after a sarin gas attack on Khan Shaykhun in Idlib Province claimed at least 80 lives.
According to AFP, the US-proposed draft statement condemns "in the strongest terms" the alleged February 1 chlorine attack in the al-Malab neighborhood of the town of Douma.
This comes as senior US officials claimed President Donald Trump is set to launch a military action if necessary against the Syrian government which they say is possibly developing new types of chemical weapons.
The officials, speaking on condition of anonymity, said last week that Syrian armed forces "evolved" their chemical weapons and made continued occasional use of them in smaller amounts since last April.
This is while the Syrian government has fiercely denied using or even possessing chemical weapons since the country’s compliance with the Chemical Weapons Convention was certified by international observers in 2013.