The Democratic National Committee's Black Caucus last night voted unanimously to express "utter dismay and extreme disappointment" with former vice president Walter F. Mondale and Sen. Edward M. Kennedy (D-Mass.) for supporting white candidates in Chicago's mayoral primary.

The two liberals, long popular with black voters, appeared before the 52-member caucus earlier to explain their endorsements in the Chicago contest, in which a black Democrat, Rep. Harold Washington, is running.

In a resolution passed without dissent, the caucus also took "serious issue" with Mondale, a 1984 presidential hopeful, for saying he plans to continue campaigning for Cook County State's Attorney Richard M. Daley in the Feb. 22 Democratic primary against Washington and Mayor Jane Byrne.

The caucus' resolution said that, were it not for Kennedy and Mondale's "exemplary records . . . on civil rights and other issues of concern to minority voters, the caucus would have been compelled to take stronger action."

The caucus is in town for the DNC's winter meeting, an event dominated by presidential politicking on behalf of Mondale, Sen. Gary Hart (D-Colo.) and Sen. John Glenn (D-Ohio).

Sen. Alan Cranston (D-Calif.), who has announced for his party's 1984 presidential nomination, yesterday threw his support in the Chicago race behind Washington. But the resolution didn't mention him.

Kennedy told caucus members on Thursday that he was fulfilling a political obligation to Byrne, who endorsed him in his 1980 race against Jimmy Carter.

Kennedy has promised not to campaign personally for Byrne, while Mondale yesterday reiterated his intention to go to Chicago on behalf of Daley.

Mondale told reporters after the session that he had made the commitment last October, before he knew who else would be in the race, because Daley is "a good friend who helped me when I needed help" in the 1980 campaign.

Mondale said he reminded the black Democrats that "I have regularly supported Democratic candidates who are black and Hispanic . . . sometimes against the organization. My record is one of fighting for an open party." But he conceded that his explanation apparently had failed to satisfy the blacks, adding, "It's controversial, and maybe more than that."

There have been implied threats from some Chicago black leaders that Mondale's stance may cost him black support in his pursuit of the nomination. But he said yesterday, "All you have in public life is your word, and I gave my word . . . . It was not a political calculation."

Cranston, who announced his presidential candidacy Wednesday, plans to endorse Washington formally at a rally in Chicago Sunday. Cranston, according to a spokesman, does not know Washington well, but was persuaded to endorse him by California Assembly Speaker Willie Brown, one of Cranston's campaign co-chairmen.

Hart, obviously enjoying Mondale's sticky situation, said he intended to endorse Byrne, Washington and Daley.

"Rather than leave the office of mayor vacant I'm endorsing all of them," he joked. "I missed out on a candidate of my own."

Meanwhile, the party's Rules Committee turned back an effort by Wisconsin Democrats to allow the state to continue its traditional "open primary system," which allows Republicans and Democrats to vote in any presidential primary, regardless of registration.

Under party rules adopted last year, delegates elected under such a primary would not be permitted to participate in the national convention. The party opposes open primaries on the grounds that large numbers of Republican voters can and have done mischief with their votes in past Democratic primaries. This has been a bone of contention with Wisconsin for the past decade.