WASHINGTON — In an aggressive move to impose President Obama’s environmental policies overseas, the Treasury Department on Tuesday largely declared an end to United States support for new coal-fired power plants around the world. The decision means that Mr. Obama’s administration will no longer contribute to coal projects financed by the World Bank and other international development banks.

“What we’re trying to do is to use the leverage associated with public finance to help developing countries move in the direction of cleaner energy,” said Lael Brainard, the under secretary for international affairs at the Treasury Department.

It is unclear how much impact the new policy will have. The United States does not have a veto over which projects in other countries get financed through organizations, and the number of coal plants built overseas with public money is small relative to the number that are likely to be built with private investment.

By leading a coalition of like-minded countries — including several European ones that have already announced similar intentions — officials said the administration would be able to influence the direction of power plant construction.