Not only there is not a good argument for considering 1948 war a genocide on Palestinians but there is a much stronger argument Arabs have tried to genocide Jews (especially to those who think who think there was a genocide in Gaza because of starvation as a weapon of war + intent):

1. In 1948 Arab forces besieged Jerusalem and they were starting to run out of food.

2. Azzam Pasha, General Secretary of the Arab League, famously threatened "a war of extermination and a momentous massacre", Fawzi al-Qawuqji, commander of the Arab Liberation Army said that "we will have to initiate total war. We will murder, wreck and ruin everything standing in our way, be it English, American or Jewish.". Hell, several have even extended the threats to not just the Jews of Mandatory Palestine, but to Jews of the Arab world as a whole, such as Iraqi prime minister Nuri al-Said("if a satisfactory solution of the Palestine case was not reached, severe measures should be taken against all Jews in Arab countries.") or the head of the Egyptian delegation to the General Assembly, Muhammad Hussein Heykal("the lives of 1,000,000 Jews in Muslim countries would be jeopardized by the establishment of a Jewish state." ). As Matiel Mughannam, head of the Arab Women's Organization in Palestine put it in an interview with Nadia Lourie in January 1948, "The UN decision has united all Arabs, as they have never been united before, not even against the Crusaders.... [A Jewish state] has no chance to survive now that the `holy war' has been declared. All the Jews will eventually be massacred. " (See Benny Morris' 1948 for sources on all of these)