"Too often members seem to believe they can gain concessions through lawsuits that they could never get at the negotiating table," Robert Lighthizer told the WTO ministerial conference in Buenos Aires.
He also criticised special treatment given to some countries because of their allegedly dubious development status.
The comments by Lighthizer, President Donald Trump's top trade representative, had been much anticipated at the conference held every two years -- the first of the Trump era.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Trump has long made the WTO a preferred target of its "America First" policy, threatening to pull Washington out of the trade organization it says is hampering its ability to compete.
"We cannot sustain a situation in which new rules can only apply to the few, and that other will be given a pass in the name of self-proclaimed development status," said Lighthizer, referring to countries like China and India.
"There is something wrong, in our view, when five of the six richest countries in the world presently claim developing country status."
Countries claiming development status at the WTO are given concessions, including longer transitions periods, before being required to fully implement agreements.
Trump has long protested that the body's multilateralism is hampering US trade at the expense of bilateral deals.
The US president has already withdrawn Washington from the Trans-Pacific Partnership (TPP) and insisted on renegotiating the North American Free Trade Agreement (NAFTA) with Mexico and Canada.
France meanwhile backed the call of the host, President Mauricio Macri of Argentina, that "WTO problems get fixed with more WTO -- not with less WTO."
"France is attached to multilateralism. We don't want that framework to be called into question," said French minister Jean-Baptiste Lemoyne, though he acknowledged that "there are improvements to be made."
Final declaration in doubt
Washington has been accused of strangling the WTO's dispute settlement system by blocking the appointment of new judges to the body.
Lemoyne expressed fears that the WTO's dispute settlement body would be paralysed in a few months.
Lighthizer told the meeting, however, that it was "impossible to negotiate new rules when many of the current ones are not being followed.
"This is why the United States is leading a discussion on the need to correct the sad performance of many members in notifications and transparency."
"Some members are intentionally circumventing these obligations, and addressing these lapses will remain a top US priority," he said.
The US stance has cast doubt on the ability of the conference to produce a joint statement Wednesday on the final day of the conference.
WTO Director-General Roberto Azevedo said Sunday that he would ask Lighthizer to show "political commitment, political will and flexibility."
"Without flexibility we will not get anywhere," Azevedo told reporters.
