Iran's President Hassan Rouhani denounced on Monday the "inaction" of the UN Security Council on Gaza, describing the conflict as a genocidal massacre of Palestinians by Israel.
His comments came at a meeting of the Non-Aligned Movement's (NAM) committee for Palestine, with several foreign ministers among officials from Qatar, Kuwait, Oman, Venezuela, Bangladesh, Sudan, Uganda and other member states.
"The savage aggression by the army of this child-killer regime (Israel), continues with a deliberate policy to commit genocide and massacre civilians and destroy infrastructure, houses, hospitals, schools and mosques," Rouhani said in Tehran.
"The inaction of international bodies, in particular the Security Council, to prevent the crimes against humanity of the Zionist regime" is to be condemned, he added.
Iran does not recognise Israel's existence and supports Palestinian Islamist groups that fight it.
Ahead of a temporary unilateral truce, Israel early Monday launched further strikes on Gaza, killing at least 16 people, including an Islamic Jihad commander, raising the Palestinian death toll to since July to 1,829, according to medics.
Just minutes into the truce a child was killed and 30 people wounded in a strike on a refugee camp in Gaza City, medics said.
The four weeks of violence have also killed 64 Israeli soldiers and three civilians, who were hit by rocket fire.
Rouhani's remarks were the latest to signal Tehran's increased ire at Israel. Iran's supreme leader Ayatollah Ali Khamenei also described Israel's actions in Gaza as genocide last week.
Rouhani on Monday criticised the "complicity of the United States and certain other members of the Security Council" with Israel, urging an international mobilisation, including the NAM countries, to "stop the war crimes" of Israel.
Israel has defended its military action as Gaza as necessary to stop Hamas rockets being fired at its people.
Last month, the speaker of Iran's parliament, Ali Larijani, told state television that Tehran had provided Hamas with the technology it has used to fire rockets from Gaza into Israel.
The commander of the Revolutionary Guards, General Mohammad Ali Jafari, on Monday said Iran was ready to provide "any form of assistance to the Palestinian resistance," according to the official IRNA news agency.
In the last major conflict in and around Gaza in November 2012, Larijani said Iran was proud to have provided "both financial and military support" to Hamas.