While leftist protesters were contained by a massive military presence in the streets, Vice President George Bush today was confronted by pointed verbal attacks on U.S. policy by some Dominican officials.

In a speech before a joint session of the Dominican legislature, Bush outlined the Soviet and Cuban threat to developing countries in the Caribbean and said that "the particular danger we in this hemisphere face is this: a totalitarianism that has to expand."

But the Dominican leaders Bush has met since his arrival yesterday repeatedly have told him that the biggest danger now faced by the Dominican Republic's three-year-old democracy is economic.

Sugar is the country's primary export, accounting for roughly 50 percent of its gross national product, and 80 percent of its sugar exports go to the United States. The U.S. Congress is considering a level of domestic price supports for American sugar producers that would, under current law, effectively impose a 50 percent tariff on sugar imports.

This, combined with already low world sugar prices and devastating increases in energy costs, forbodes doom for the Dominican economy.

While President Antonio Guzman, who met with Bush for an hour today, has voiced the same concerns, he said he had asked the United States for Washington's close cooperation to prevent social conflicts from turning into violence. He described such social conflicts as "at times generated by economic pressures."

Chamber of Deputies President Hatuey de Camps, a leader of the more liberal wing of Guzman's Democratic Revolutionary Party that is currently challenging the president's choice for his successor in elections next spring, put the situation in starker terms.

"The protective measures adopted by the United States against imported sugar, together with a policy of high interest rates, constitute the most important cause for the fall of our sugar price, which means a blow without precedent to the Dominican economy," de Camps said in a speech before the legislature.

On the subject of the Soviet Union and Cuba, de Camps said that the Soviets pay a consistent 40 cents a pound for Cuban sugar and and Cubans buy Soviet oil for about $12 a barrel, while the United States imposes a tax on Dominican sugar, which only brings about 12 cents on the current world market. Meanwhile, Santo Domingo has to buy oil at almost $35 dollars a barrel. What Soviet aid has done for Cuba from this perspective is make it the biggest, most effective competitor in the regional sugar market.

English-speaking Caribbean nations have worked out special arrangements with the Commonwealth and the European Community, but the Dominican Republic remains faithful to the United States -- and suffers as a result.

De Camps openly questioned why the United States and other large consumers in the region cannot, or will not, try to assure a stable market to their allies.

Despite the Reagan administration's consistent claim that the best solution for the world's economic problems is to cure the current sickness of the American economy, de Camps said flatly that the economic crisis of the highly developed, capitalist United States simply "does not have the same roots and solutions" as that of an underdeveloped country like the Dominican Republic with limited resources, facing unprecedented capital flight and a vast poor population reaching "uncontrollable proportions."

Helvio A. Rodriguez, president of the Dominican Senate, explained what the Dominicans want: preferential treatment, including an annual quota of 800,000 tons of Dominican sugar at a price similar to that given domestic U.S. producers.

In apparent response to Dominican concerns, Bush offered a slight change in his prepared text to say that once he finishes his trip, which goes on Tuesday to Colombia and Brazil, he will discuss sugar "in person with the president of the United States."