WASHINGTON — The International Monetary Fund on Tuesday lowered its estimates for United States economic growth for this year and next, and urged policy makers to do more to help the housing sector and support the tepid recovery.

In its annual assessment of the American economy, the fund also had a sharp warning for Washington: avoid the fiscal cliff at the end of the year, when the Bush-era tax cuts expire and mandatory spending cuts across the government go into effect. The sudden shock could be enough to put the country back into recession, the fund warned, with global repercussions.

In a news conference, Christine Lagarde, the fund’s managing director, also said that Congress should “promptly” raise the debt ceiling to avoid spooking the global debt markets and raising the country’s borrowing costs. The government is expected to hit its statutory borrowing limit late this year.

Should policy makers fail to ease the end-of-the-year fiscal blow and raise the debt ceiling, “the domestic effects would be severe, with negative spillovers to the rest of the world,” warned Ms. Lagarde.