Worsening economic conditions for black Americans are providing all of the ingredients for wide-spread social unrest, including possible riots, the president of the National Urban League said yesterday.

"Black America today verges on the brink of disaster," league President Vernon E. Jordan said in issuing his organization's annual report on economic and social conditions affecting the nation's blacks.

He said the "possibility of a fresh recession hitting a black community that has not recovered from the last one," combined with a widening black-white employment and income gap, is fraying the country's social fabric, and that "frayed social fabric cannot sustain the racial and class pressures a new recession would bring."

Asked if that meant that the league anticipated a renewal of the racial violence of the 1960s, Jordan said: "All of the ingredients are there to give impetus to that kind of thing. But I hope nothing like that would happen, because we know from past urban conflagrations that we [blacks] are the ones who do all the suffering when that happens."

Jordan said the league now finds "increased anger and frustration, a sense of dispossession" among many impoverished blacks. But he said if disaster should strike, if all of the league's worst economic predictions come true, "I don't know what will happen, and that's what worries me."

Jordan, who in the past has criticized President Carter for failing to respond to black economic complaints, yesterday said the Carter administration "has demonstrated a capacity for responsiveness" in dealing with current problems. However, he said the administration's efforts have been frustrated by a "recalcitrant, insensitive Congress."

And even those administration efforts that have succeeded, such as the passage last year of the Humphrey-Hawkins jobs bill, have been "insufficient when measured against the magnitude of the problems," Jordan said.

Jordan said the extent of the crisis facing black Americans is documented in the league's 1979 report, which is just as bleak as the organization's State of Black America report last year. For example, the latest report says:

The difference between black and white families' median income is widening. In 1970, black families earned a median income of $9,799, compared with $15,974 for white families. In 1977, blacks earned $9,563, compared with $16,740 for white families.

Black unemployment is at its highest level in history. Here, the report speaks of total unemployment -- the number of blacks out of work and looking for jobs as well as the discouraged unemployed who have stopped their job search. Total unemployment for blacks is 23.1 percent, the report said.

The black-white unemployment gap is widening, a contention supported by Department of Labor statistics.

Twenty-eight percent of the nation's black families live in poverty, compared with 7 percent of white American families.

The report noted, as did last year's league survey, that the nation's black middle class continues to grow economically and numerically. But too often the black middle class is cited by whites as proof that most blacks are making it, the report said.

"Contrary to some depictions in the news media, increasing proportions of black families are not making it economically today... The numbers of poor persons in the black community are at their highest level," the report said.

The report also cited a new negativism in the American electorate, which, it said, threatens to destroy social programs and further erode black gains in hiring and education. The new mood is represented by the recent election of a more conservative Congress and by the approval of proposals like Proposition 13, limiting the use of property taxes for public services and social programs.

"The economic status of blacks has been closely tied not only to the state of the economy, but to the state of government budgets," the report said. Now, it continued, "these programs have been caught up in bureaucratic bickering, congressional conflicts and the taxpayer revolt.... Neoconservatism and tight budgets threaten to put them in limbo forever."

Instead of working with the administration to increase jobs for the poor and to improve education and training opportunities, many members of Congress spend their time on "dumb issues" like trying to expel black Rep. Charles C. Diggs Jr. (D-Mich.), Jordan said.

Diggs was reelected in November after being convicted on charges stemming from a House employes' salary kickback scheme. The case is on appeal.

Jordan said he was not speaking on the merits of Diggs' case. "I just think it's dumb to worry about this when we have so many other problems," he said.