Faced with the prospect of what they view as a hard-line conservative government in Washington, Nicaragua's revolutionary leaders are moving to reassure the banking and business communities that they do not want Nicaragua to become isolated from the Western economic system as Cuba did.

Earlier this month Finance Minister, Joaquin Cuadra traveled to New York to make the first $20 million payment under the new terms agreed upon in Spetember for Nicaragua's debt of about $582 million with 115 private banks.

Cuadra then came to Washington to sign two important development loans -- one from the World Bank for $5 million and another for $65 million from the Inter-American Development Bank.

Nicaragua "rolled out the red carpet" for a World Bank mission that recently visited the country, a bank source said, and now the revolutionary government has surprised financial observers by inviting a mission from the International Monetary Fund to visit Nicaragua in the middle of next year.

The Sandinista revolutionaries who overthrew Anastasio Somoza in July 1979 always have criticized the IMF for imposing strict conditions on its loans and blocking serious social and economic change. s

Cuadra said Nicaragua is not planning to ask for an IMF stand-by loan but pointed out that the country has kept up to date on its quotas and used the facilities it is eligible for as a member of the fund.

The payment to private banks made in New York last week opens the way for renegotiating about $150 million owed by private Nicaraguan companies that were nationalized when the Sandinistas took power -- primarily the country's banks.

At the same time, Cuadra said, Nicaragua is nearing agreement with the Canadians and North American companies that were nationalized when Somoza fell.He said the government also was working out an accord with Castle & Cooke, which exports bananas produced on Nicaragua's western coast.

Other reliable sources said the private landowners and Castle & Cooke had not reached agreement with the government on its effort to take over banana marketing.

The government is even drafting a foreign investment law to be promulgated early next year.

"They want the multinationals to come in," a financial source said. "That's like working with the devil himself."

But all is not rosy in Nicaragua's economic relations with the industrialized countries. An effort to renegotiate about $200 million in bilateral debts with the United States and four other countries failed at a Paris Club meeting in October.

But U.S. and Nicaraguan sources have said the United States insisted on an IMF standby program, which the Nicaraguans could not accept.

During the first year and a half of trying to rebuild the country's economy following the civil war that brought the Sandinistas to power, the total foreign debt has risen from $1.6 billion to more than $2 billion, Cuadra said. He added, however, that the new loans were for development projects and all were granted at concessionary terms, at an average interest rate of a little over 4 percent.

All but $15 million of the $75 million lent by the United States after a lengthy debate in Congress has been spent, according to sources here. The remaining $15 million has not yet been paid to Nicragua.

Cuadra said the government does not want to contract any short-term commercial debts, a point that may cause friction with Nicaraguan businessmen, who need hard currency loans.

The fragile alliance between Sandinista revolutionary and Nicaraguan business community has deteriorated in the year and a half since Somoza's fall.

The most serious blow was the killing of Jorge Salazar, an important business leader, by government security forces last month. Some Nicaraguan businessmen and opposition politicians called the killing a "political assassination," but the government insists Salazar was killed in a shootout after a man accompanying him fired at police.

Cuadra said Salazar was involved in a conspiracy against the government that had been infiltrated by a Sandinista commander. Salazar was being followed by security forces and was about to turn over a load of weapons when the man with him spotted police following them and opened fire.

Salazar, who was not armed, was killed. The other man was arrested, tried, and jailed, Cuadra said.

While Nicaraguans still are trying to have good economic relations with the West, they also are seeking new trade partners and aid suppliers.

A second high-level delegation recently visited the Soviet Union and other socialist countries. So far Nicaragua has signed some trade and technical assistance agreements with Soviet bloc nations but has received no substantial financial assistance.

The Sandinistas have made it clear that they fear the Reagan administration will try to "destabilize" their economy, as they believe the Nixon administration did in Chile to cause the fall of the leftist government of Salvador Allende.

Defending the purchase of East German trucks -- widely criticized in Nicaragua, Cuadra said, "We did it in case they [the United States] put a blockage on spare parts."

Both Chile and Cuba had serious difficulties when they were unable to obtain spare parts of U.S.-made vehicles and other equipment.