PANAMA CITY, AUG. 8 -- A Gallup poll released today found that 75 percent of city-dwelling Panamanians want military strongman Gen. Manuel Antonio Noriega to resign from his post.

Only 13 percent of 638 Panamanians polled Aug. 1 to 4 in Panama City and Colon, the nation's second-largest city, said Noriega should remain as Panamanian Defense Forces commander-in-chief, the military's highest job.

The poll was conducted by a Costa Rica-based firm, CID, the Gallup International affiliate for Central America and Panama, whose general manager is Carlos Denton. It is the first independent sounding of public views in this country since anti-Noriega protests erupted two months ago.

The survey appeared to reveal even wider rejection of the general, Panama's de facto ruler since 1983, than had been evident from recent street demonstrations.

On Thursday, a hastily summoned opposition rally snowballed during the day to draw tens of thousands of demonstrators. But a progovernment march the previous week, in honor of the late nationalist ruler general Omar Torrijos, drew a similarly large crowd, although it included thousands of government employes.

"No poll, no matter how prestigious the firm, could accurately reflect what those same 600 or so Panamanians will think 72 hours from now," said Noriega's spokesman, Maj. Edgardo Lopez.

"The dynamic of the situation is constantly changing. And if Denton conducted his poll in areas outside the cities, the result would be totally different in favor of the general."

Denton said in an interview that the $16,000 poll was paid for by about a dozen wealthy private businessmen who wished to remain anonymous.

"They believe if they are identified they may be forced to leave Panama," Denton said. He noted that internationally recognized ethics governing political polling normally require that the sponsor's identity be made public.

A businessman familiar with the executives who ordered the survey said they are opponents of Noriega who saw the poll as one way to fight back against a press blackout that the government imposed on them by shutting all opposition radios, newspapers and weeklies.

The results of the survey are not likely to be publicized in the Noriega-controlled media, but the poll's sponsors were said to be confident that the results would be circulated in Panama by word of mouth.

Denton said the sponsors were not involved in writing, conducting or tabulating the 40-question interviews.

Polls that CID conducted in recent years in Central America have proved reliable. For example, Denton correctly predicted within a percentage point that the Christian Democrats led by President Jose Napoleon Duarte would win a majority in the 1985 National Assembly elections in El Salvador, when most other observers were reporting that the party's popularity had plunged.

Denton, who has conducted polls for the U.S. Embassy in El Salvador, said yesterday, "The U.S. Embassy in Panama was not involved and hasn't yet seen the results."

Some results:Fifty-nine percent of those polled said President Eric Arturo Delvalle should also step down if Noriega resigns. Sixty-four percent responded that the government is functioning poorly or very poorly. Seventy-nine percent said Noriega makes the government's decisions, while only 8 percent saw Delvalle as making them. Delvalle was put in power by Noriega in 1985. In an interview yesterday with the Los Angeles Times, Delvalle distanced himself from Noriega by criticizing recent harsh police measures against opposition media and business groups and "If Denton conducted his poll in areas outside the cities, the result would be totally different in favor of the general."

-- Spokesman Maj. Edgardo Lopez

comparing Panama to the last days of the Nicaraguan dictatorship of Anastasio Somoza. Fifty-four percent said the National Assembly, which is dominated by members of the Democratic Revolutionary Party, the official armed forces party, should also resign to pave the way for new elections. Seventy-seven percent said the 1984 election, the last nationwide vote, was fraudulent. The current crisis was sparked when Noriega's second-in-command, Col. Roberto Diaz Herrera, was fired in June and publicly accused Noriega of rigging the elections, along with allegations of the general's involvement in murder and corruption. Forty-five percent saw it as unlikely that Washington will live up to the 1977 Panama Canal Treaties. Only 1 percent believed that U.S. aid to Panama should be used to train the armed forces. The $26 million in U.S. military and economic aid to Panama for this year has been frozen since mid-July.

The poll was conducted in person and by phone among adults in Panama City, the city of Colon on the Atlantic Ocean side of the isthmus and suburbs in between. About three-fifths of the population of 2.5 million live in the area. The poll had a 4-point margin of error.