President Barack Obama addresses the 64th session of the General Assembly for the first time Wednesday at United Nations headquarters.

New York ? President Barack Obama challenged world leaders Wednesday to shoulder more of the globe’s critical burdens, promising a newly cooperative partner in America but sternly warning they can no longer castigate the U.S. as a go-it-alone bully while still demanding it cure all ills.

“Those who used to chastise America for acting alone in the world cannot now stand by and wait for America to solve the world’s problems alone,” said Obama in put-up-or-shut-up comments before a packed U.N. General Assembly hall. “Now is the time for all of us to take our share of responsibility for a global response to global challenges.”

In his first appearance before the group, Obama promised the U.S. would reach out in “a new era of engagement based on mutual interest and mutual respect,” but he also wagged a rhetorical finger at leaders who spend much of their time at international gatherings excoriating the U.S. He said “an almost reflexive anti-Americanism” that swept the globe under the administration of his predecessor, George W. Bush, is not “an excuse for collective inaction.”

“Nothing is easier than blaming others for our troubles and absolving ourselves of responsibility for our choices and our actions,” he said.

And yet, directly following Obama at the podium was Libyan leader Moammar Gadhafi, who railed against the U.N. Security Council, which includes the U.S., calling it a “terror council” and accusing it of treating smaller nations as “second class, despised.”

U.S. presidents — Bush included — have come to the United Nations year after year with a wish list of action items and preaching the gospel of working together. The U.S. is rich and powerful, but cannot solve problems without help, they say, whether Democrat or Republican.

So Obama’s message was not new.

But it was delivered in an unmistakably new, more humble tone.

Following a president criticized for making my-way-or-the-highway “requests” of allies, Obama didn’t demand so much as he chided and cajoled. It’s now an inextricably interconnected world, he said, so that each country’s problems become the others’.

“In the year 2009 — more than at any point in human history — the interests of nations and peoples are shared,” Obama said.

Following a president pilloried for arrogance, Obama talked more modestly about the United States.

To be sure, he listed American contributions. But this was no chest-thumping bragging; instead it was a more lawyerly argument aimed at convincing the jury of Obama’s world peers that the U.S. has heard the complaints and, under his leadership, is addressing them. That ranges from banning torture to winding down the Iraq war, working to rid the world of nuclear weapons, aggressively pursuing Mideast peace and bringing new energy to the battle against climate change.

And he delivered the message that America will not behave as if it is better.

“No one nation can or should try to dominate another nation,” Obama said. “That is the future America wants — a future of peace and prosperity that we can only reach if we recognize that all nations have rights, but all nations have responsibilities as well.”