The United States “reserved its position” on the text about commitments made by G7 countries under the 2015 Paris climate accord, said Carlo Calenda, the Italian minister for economic development, who chaired the meeting in Rome.
Lacking unanimity, Italy, which currently presides the Group of Seven, decided against proposing the joint statement, Calenda said.
The Paris Agreement, endorsed by members of the UN Framework Convention on Climate Change (UNFCCC), is a bedrock of international action against man-made global warming.
It vows to cap warming to “well below” two degrees Celsius (3.6 degrees Fahrenheit) compared to late 19th-century levels – an effort that scientists say will require massive cuts in carbon emissions from coal and other fossil fuels.
It also pledges to provide hundreds of billions of dollars in aid for poor countries badly exposed to drought, flood, rising seas and other climate impacts.
In March, President Donald Trump signed an executive order rolling back some of the previous Democratic administration's policies on carbon emissions and climate change.
Experts have said his plan, which eases emissions limits for coal-fired power plants and scraps more stringent vehicle pollution standards, almost guarantees that the United States will fail to meet its commitments under the Paris Agreement.
Trump has also said he does not intend to honour promises made by the administration of his predecessor, Barack Obama, to provide financial aid under the Paris accord.
However, Trump's team is also deeply divided on whether to withdraw from the pact, according to US media reports. On March 30th, the White House said a decision on whether to withdraw would be made ahead of the G7 summit in Italy in late May.
Under Obama, the United States, the second biggest carbon polluter, provided critical impetus for the Paris deal by concluding a precursor deal with China, the number one emitter.
The Group of Seven, gathering the biggest western democracies, comprises Britain, Canada, France, Germany, Italy, Japan and the United States.