Harper's office said the prime minister called Obama to offer his congratulations and used "the opportunity to convey to the President the importance of the White House and Congress working together to tackle the U.S. fiscal situation."
A package of tax increases and government spending cuts will occur unless Congress acts by Jan. 1. Investors see it as a serious threat to the global economy.
The prime minister and the president spoke on the phone for 10 minutes. Harper is in India on a trade mission.
Canada and the U.S. have the largest trading relationship in the world. Mark Carney, the head of Canada's central bank, called the so-called fiscal cliff the most imminent threat facing the Canadian economy. Finance Minister Jim Flaherty said if there is no agreement it would push the U.S. into recession quickly and the Canadian economy would be sure to follow.