Tunisian President Kais Saied presented US counterpart Donald Trump's senior Africa adviser with photographs of starving children in Gaza, official video of their meeting posted late on Tuesday showed.
Saied told US envoy Massad Boulos, who is also the father-in-law of Trump's daughter Tiffany, that "it is time for all of humanity to wake up and put an end to these crimes against the Palestinian people."
"I believe you know these images well," Saied was seen telling the envoy as he showed a photograph of what he described as "a child crying, eating sand in occupied Palestine."
Saied showed Boulos several more images, saying that Palestinians in Gaza were subjected to crimes against humanity.
Israel is facing mounting international pressure over the catastrophic humanitarian situation in the Palestinian territory, where more than two million people have endured 21 months of devastating conflict.
"It is absolutely unacceptable," Saied was heard saying as Boulos stood silently, occasionally nodding. "It is a crime against all of humanity."
More than 100 aid organisations warned on Wednesday that "mass starvation" was spreading across the Gaza Strip and that their own colleagues were suffering acutely from the shortages.
The head of Gaza's largest hospital said on Tuesday that 21 children had died from malnutrition and starvation in the Palestinian territory in the previous three days.
Israel says humanitarian aid is being allowed into Gaza and accuses Hamas of exploiting civilian suffering, including by stealing food handouts to sell at inflated prices or shooting at those awaiting aid.
Following his visit to Tunisia, Boulos flew on to the Libyan capital Tripoli on Wednesday, Tunisian media reported.
Agence France-Presse