Aid agencies have accused Israel of bombing schools where children were waiting to receive polio vaccinations.
The WHO, UNICEF and affiliated organisations have postponed the final stage of the rollout, with 120,000 children in Northern Gaza awaiting the jab.
It comes as 17 people were reportedly killed in an Israel airstrike on a school in Nuseirat on Thursday.
Trócaire CEO Caoimhe de Barra said Israel’s actions are ‘intolerable’.
“Israel continues to bombard schools where people are sheltering, including schools where people were waiting for the vaccines,” she said.
“The three hospitals that had continued to function in northern Gaza now have no access to medical supplies.
“They were ordered to evacuate. They have been ordered to remove all patients from those hospitals.
“It's simply intolerable. The number of massacres that have happened is almost beyond counting at this point.”
Military strikes in Iran
This comes as Israel has confirmed that it targeted Iranian military sites with airstrikes overnight.
Daniel Hagari, Israel's rear admiral, said the country’s defensive and offensive capabilities are ‘fully mobilized’.
“If the regime in Iran were to make the mistake of beginning a new round of escalation, we will be obligated to respond,” he said.
“Our message is clear. All those who threaten the state of Israel and seek to drag the region into wider escalation will pay a heavy price.”
The Israeli Defense Forces says it carried out the attack in response to hundreds of ballistic missiles fired into its country from Tehran earlier this month.