President Trump used his first official visit to the United Nations on Monday to criticize the world body for not living up to its “potential,” and urged member nations to reject “business as usual” and take “bold stands.”

“In recent years, the United Nations has not reached its full potential because of ​​bureaucracy and mismanagement​,​”​ Trump said during a meeting about reforms.

Despite a ballooning budget and a doubling of staff since 2000, Trump said, “We are not seeing the results in line with this investment . . . The UN must hold every level of management accountable, protect ​whistle​blowers and focus on results ​rather than on process.”

The president spoke in a measured tone, keeping to his prepared remarks and praising UN Secretary-General Antonio Guterres as an ally in the reform effort.

“​W​e encourage all member states to look at ways to take bold stands at the United Nations with an eye toward changing business as usual and not being beholden to ways of the past, which were not working,” Trump said, pledging the United States would be a full partner.

The president also said none of the 193 member nations should shoulder a “disproportionate share of the burden — militarily or financially.”

And he called for creating “clearly defined goals and metrics for evaluating the success” of the UN’s peacekeeping mission around the globe.

​With the changes, Trump said, “I am confident that if we work together and champion truly bold reforms, the United Nations will emerge as a stronger, more effective, more just and greater force for peace and harmony in the world.”

The US is the largest contributor to the UN, paying 25 percent of its operating budget and 28 percent of the separate peacekeeping budget.

In his own remarks, Guterres agreed that the UN bureaucracy had spun out of control.

“I even sometimes ask myself whether there was a conspiracy to make our rules exactly what they need for us not to be effective,” he said.

In his opening remarks, Trump pointed out that he decided to build the Trump World Tower on First Avenue because of its proximity to the UN.

“It was only for the reason the United Nations was here that that turned out to be such a successful project,” he said.

Trump speaks to the UN General Assembly on Tuesday and he said his main message will be “Make the United Nations great.”