Citing his state's success at building housing for lower-income citizens who otherwise would be kept from participation in the American "dream" of home ownership, Virginia Attorney General Marshall Coleman sharply denounced recent proposals yesterday to eleminate tax exemption of bonds to finance single-family housing.

As members of the House Ways and Means Committee prepared to meet today and Friday on the controversial mortage tax bond issue, Coleman told a Washington investment group that any such federal action would amount to "usurpation" of state powers, possibly in violation of the Constitution.

Discarding his scheduled topic - "The Financial Health of Virginia" - Coleman ripped into Ways and Means Chairman Al Ullman (D-Ore.) for his introduction on April 25 of legislation to crack down on the use of tax-exempt state and local government bonds to finance low-interest mortgage loans for single-family homes not negotiated prior to April 24.

The legislaton - later endorsed by the Carter administration and Senate Finance Committee Chairman Russell Long (D-La.) - "is a movement in the direction of the federal government being arbiter of what should be public policy, a usurpation of the states' rights to manage their own affairs . . . by overreacting to problems and abuses" in some localities, Coleman said in a speech typical of the state's rights concept of government long popular in Virginia politics.

Although Coleman didn't discuss Virginia's economy in general in his speech yesterday to the Municipal Finance Forum of Washington, there were enough other reports yesterday to fill that void. In upheat announcements:

Virginia's Employment Commission said unemployment in the Commonwealth took a sharp nosedive between March and April. The jobless rate fell to 4.5 percent from 5.5 percent, a decline that state officials attributed to strong employment gains in construction, agriculture and retail wholesale trade. A total of 110,300 Virginians were out of work in mid-April for the lowest April jobless rate since 1974. In Northern Virginia, unemployment declined to 3.2 percent.

The College of William and Mary said Virginia's economy began to "pick up steam" in April, with virtually all standard indicators up in nearly all metropolitan areas. Retail sales rose 14.3 percent, and building permits rose 14 percent.

In Tokyo as head of a 12-person Virginia economic mission, Gov. John Dalton called for increased quotas for Virginia tobacco and other agricultural imports to that country and revealed plans to establish a state development office in Japan in about a year provided the legislature authorizes funding. A similar office in Brussels has attracted 101 European firms, investments of $700 million and 18,500 jobs in the past decade.

In his talk here, Coleman vowed to continue defense of "the principles of federalism, increasingly under attack from forces and agencies in Washington."

More than 8,500 single-family houses have been constructed in the last six years with the assistance of tax-exempt mortgage bonds, Coleman said. More than 90 percent of the families involved near had owned a house before, and average family incomes for citizens who participated was $13,800 a year. "Private lenders said they were not eligible for conventional mortgage financing," the state official added.

Noting that many of the abuses which led to the current move to ban such financing took place at the local government level, Coleman called on the states to establish guidelines to prevent issuing such bonds for relatively affluent house buyers.

Last year, state and local governments issued $3.3 billion in mortgage revenue bonds, and more than that amount was issued in the first four months of 1979. The bonds provide buyers with funds at 2 percent or 3 percent below current market rates but not all of the funds have been earmarked for low-income and moderate income buyers; in California, state bonds reportedly financed $165,000 condominiums.

Rather than "tearing down" state programs such as the Virginia Housing Development Authority, the most federal legislators should attempt is "broad" guidelines to pinpoint income limits and maximum sales prices for such assistance, Coleman said yesterday. CAPTION: Graph, shows one-year changes in major Virginia cities' economic activity. The Washington Post