Asked about life in Gaza, Mr Regev acknowledged the Palestinians "live a very hard life", but blamed Hamas, claiming it does nothing for the people but "invests its efforts in a holy war - their words, not mine - against Israel".
"We were horrified at reports this morning that an eight-month old baby girl died from inhaling tear gas at the protests on Monday, with our staff on the ground telling us that the family was nearly a kilometre from the security fence when this happened", Save the Children's Occupied Palestinian Territory Country Director Jennifer Moorehead said.
More than 100 Palestinians have been killed and hundreds wounded by live fire during a series of weekly protests led by Hamas, the militant group that rules Gaza.
Dozens of injured Palestinians are still waiting for surgery at Gaza's main hospital, where patients with gunshot wounds filled wards and hallways.
Leila died at the hospital on Tuesday morning and her funeral was held later that day, which marked the day of "Nakba" that commemorates the more than 700,000 Palestinians who were expelled from their lands by Israeli forces back in 1948.
Mariam, herself only 17, explained that she had a dentist appointment "so I left Leila with my brothers at home". But her brother Ammar, 11, took the baby to the border - a flashpoint for violence - after mistakenly thinking Miss al-Ghandour was there with the child's grandmother, Heyam. They stayed only a few minutes, Heyam insisted, before tear gas rained down on them.
Theresa May yesterday described the loss of life in Gaza as "tragic", and called for an inquiry into the deaths. "We got away from the gas and gave Leila to my sister and went looking for two other children so we could leave".
At first, the baby's parents thought she was merely sleeping.
"Parents of those who have been injured tell us they don't know how to support their children", said Jennifer Moorehead, Save the Children's Occupied Palestinian Territory Country Director. The PM said the violence was "destructive to peace efforts".
Foreign Secretary Boris Johnson said peaceful protests were "being exploited by extremists".
But during a UN Security Council meeting, U.S. ambassador Nikki Haley said: "No country in this chamber would act with more restraint than Israel has". Meanwhile, her family told the media her uncle had taken her towards the protest area in search of her mother.