The United States, Israel, and seven other countries voted against the ceasefire resolution, while 13 countries abstained.
A majority had important roles in UNRWA schools, serving as principals or deputy principals.
Two WCK workers, who spoke on condition of anonymity, said the termination was for "security reasons."
Officials reportedly confirmed that hostage/ceasefire negotiations were privately progressing.
Argamani's remarks came as she showed the audience a video published in January in which she appeared in captivity.
Israeli strikes across the Gaza Strip killed at least 19 Palestinians overnight and on Tuesday, medics told Reuters.
In response to a speech by the mother of hostage Omer Shem Tov, Gerardo said that be it through prayer or activism, “each one of us has a role and a mission,” to help bring back the hostages.
Four soldiers killed in southern Lebanon, first casualties since ceasefire • Three soldiers killed in Gaza strip
Twelve additional soldiers were wounded in the same incident.
He also pushed back against deals that would result in the release of some hostages, saying they compromised military achievements.