The Carter administration's efforts to halt the sealift of Cuban refugees ran into angry resistance yesterday from Cuban-American leaders, many demanding that the United States admit all the refugees and help overthrow Fidel Castro's communist regime.

At a State Department meeting with prominent Cuban-Americans, senior administration officials pleaded for an end to support of the impromptu sealift that the U.S. government fears could swamp the country with untold thousands of people seeking to get out of Cuba.

The administration admitted that the sealift cannot be checked if the Florida Cuban community continues to encourage and finance it, but its pleas were turned aside by the Cuban-Americans, who said they could do nothing even if they wanted to.

Instead, many of the guests stormed out of the meeting, chaired by Deputy Secretary of State Warren M. Christopher, to denounce the U.S. government for turning its back on what they called "the victims of communist oppression."

In a series of impromptu and angry news conferences that sprawled over the vast State Department lobby, the Cuban-Americans called for a return to the policy of the 1960s, when hundreds of thousands of Cubans were allowed to come into the country.

The group, calling itself the Cuban Patriotic Junta and claiming it spoke for the majority of those at the meeting, released a policy statement saying the United States should "provide the adequate means of transportation for all Cubans wishing to leave the island" and give them "the same legal status as other Cuban refugees, rather than considering them as illegals."

One of the U.S. officials at the meeting, Jack Watson, a senior presidential aide, admitted, with considerable understatement, that "we did not make much progress," and added that the Cuban-American guests mainly wanted " to talk about a long-term strategy for dealing with Castro."

Watson ritualistically said he considered the meeting "useful" as a forum for hearing the views of the Cuban community. But the reaction of the guests to what was said at the closed session made clear that the administration faces a tough fight to achieve what a senior State Department official called "the need to educate the Cuban community to the larger national interests at stake."

The official, who declined to be identified, spoke with reporters at a background session before the meeting. He reiterated the administration's position that the United States, for economic and social reasons, cannot accept Cuban refugees in the massive numbers that came in the past.

He said the sealift, which sprang into being a week ago after Castro's government indicated that anyone wishing to leave Cuba was free to go, violated U.S. immigration laws, and said President Carter was determined to have the law enforced.

As of yesterday, the official said, 2,-100 Cubans had arrived in 30 small boats and one airplane, their trips financed by members of the large Cuban community in Florida. The inpouring, most of which has arrived via Key West, was described by the official as "a business with some people trafficking in human lives."

He noted that the numbers arriving threaten to outdistance vastly the places legally available for new immigrants from Cuba -- roughly about 9,-500 at present -- and warned that, since those coming in are illegal aliens, they theoretically could be sent back to Cuba if they do not qualify for political asylum.

However, the official added, there is little likelihood that any sizable numbers will be deported, partly because of humanitarian considerations and partly because of the legal difficulties involved in prevailing against aliens who resist deportation.

The administration's strategy is to limit the number of Cubans who make it to the United States by choking off the sealift to the maximum degree. The official noted that fines of $1,000 for each person brought in illegally are being levied against boat owners engaged in the traffic, and he warned that the government will move to stiffer penalties, such as criminal prosecutions, if necessary.

However, noting that Florida "has a very large coastline" and that "our enforcement capability is limited," the official said that any attempt to shrink the boat traffic could not succeed without the cooperation of the Cuban-Americans paying to bring their friends and relatives off the island.

For that reason, he said, it is imperative to "educate" the Cuban-American community to the fact that is actions are helping Castro put the United States in a bad light and avoid cooperating with the international community to find an organized solution to the refugee problem.

Yesterday's State Department, meeting was the first step in that "education campaign." U.S. officials said the White House shortly will issue a statement on the problem, possibly as soon as today; and Victor Palmieri, the State Department's coordinator of refugee affairs, left yesterday for Florida, where he is to meet with state and municipal officials and seek to continue the dialogue with the Cuban community.

In the waters between Cuba and Key West, increasingly choppy weather was making the 90-mile passage more dangerous, and the Coast Guard reported a big increase in distress calls from boats encountering high winds and waves in the Florida Straights.

Some of the boats reaching Key West reported that an estimated 1,000 vessels from Florida were anchored at the Cuban port of Mariel, near Havana, waiting to load still more refugees and attempt the crossing.

Crewmen said that Cuban food and trinket vendors were having a field day at Mariel, selling ham and cheese sandwiches for as much as $5 apiece and chicken and rice lunches for $7.

But as the boat pulled in to the docks at an old naval station in Key West, where refugees are processed by U.S. Customs and Immigration officials, the scene was unvarying from earlier arrivals.

Automobiles on the docks would honk horns in salute; arriving boats would signal back, and the refugees, mostly standing tightly packed on the decks, waved two-fingered "V" signs and chanted 'liberatad, libertad."

As the Cubans filed off the boats, the scene was a familiar repeitition of earlier arrivals. Some wept without restraint, some jabbered news from Cuba to anyone within earshot, others were cowed into silence by the emotion of it all.