Demonstrators protested a pending International Monetary Fund loan to the Nicaraguan government yesterday by occupying an IMF office. Some also slipped past the building's security guards to distribute leaflets on its 12 floors while others marched before the main entrance at 700 19th St. NW.

More than 60 people were involved, including 20 who entered the building. Most of these were led out by security guards after a few minutes. But four-Sister Betty Campbell, Robert Cohen, Ruth M. Fitzpatrick, and Philip E. Wheaton-occupied a 10th-floor office for almost seven hours. They were removed by Washington police at 6:45 p.m. and charged with unlawful entry.

The protest was organized by the D.C. Coalition in Solidarity with the Nicaraguan People, an ad hoc group including Nicaraguans, clergy and politically active U.S. citizens opposed to the regime of Nicaraguan President Anastasio Somoza.

The protesters claim the proposed loan of more than $40 million and an austerity program designed by the IMF to bolster Nicaragua's nearly bankrup economy would only help to keep Somoza's dictatorship in power.

Kay Stubbs of the Washington Office on Latin America said sources in the IMF and the State Department have conceded that the loan is politically motivated. The Carter administration has been trying for months to persuade Somoza to step down, but recently has appeared to soften its stand.

An IMF spokesman said, "We don't deal with politics but with countries as they are." The loan, known as a standby arrangement, is much the same as those made to 19 other countries covering the whole political spectrum, and in any case is weeks away from formal approval, the spokesman said.