"If the United Nations wants to remain relevant, it will need to improve its effectiveness and enhance its reliability," he said.
Modi said that today, all kinds of questions have been raised about the UN.
"We have seen such questions being raised, related to the climate crisis and during the COVID-19 pandemic," he said.
The WHO, the UN's health agency, has faced criticism since the Covid-19 outbreak first surfaced in China in December 2019.
WHO faced criticism that it was mishandling the crisis.
Former US president Donald Trump slammed the WHO as a "puppet" of China and accused it of covering up the start of the outbreak and allowing the virus to spread around the entire world.
Also Read: Come, make vaccine in India: PM Modi at UN General Assembly
"The proxy war going on in many parts of the world, terrorism and the recent crisis in Afghanistan have further highlighted the seriousness of these questions," the Prime Minister said.
"With regard to the origin of COVID-19 and the ease of doing business rankings, institutions of global governance have damaged the credibility they had built after decades of hard work," he said.
The World Bank recently said it was discontinuing its flagship Doing Business publication, citing data irregularities in recent editions of the global business climate index.
The decision was taken after a probe of data irregularities allegedly due to pressure by some top bank officials to boost China's ranking in 2017 came to light.
The World Bank said in a statement that the decision came after internal audit reports had raised "ethical matters, including the conduct of former Board officials as well as current and/or former Bank staff" and a board investigation conducted by the law firm WilmerHale.
The WilmerHale report cited "direct and indirect pressure" from senior staff in the office of then-World Bank President Jim Yong Kim to change the report's methodology to boost China's score.
"It is essential that we constantly strengthen the UN, in order to safeguard global order, global laws and global values," Modi said.
Also Read: Confident about LIC listing taking place by fourth quarter of this year: CEA K Subramanian