Holding campus rallies, teach-ins, vigils and forums on foreign policy, college students here and across the country yesterday squared off on the question of whether the U.S. military action in Grenada a year ago was a rescue mission or an invasion.

The demonstrations against and supporting the U.S. action in Grenada, many of which drew smaller numbers of counterdemonstrators or hecklers, marked the anniversary of the American intervention.

With the presidential election less than two weeks away, organizers of both types of events also sought to underscore either the success or the failure of the Reagan administration's foreign policies.

In the District, there were events held protesting the intervention at American University and Howard University and a rally supporting it at Farragut Square.

[The Grenadian former ambassador to the Organization of American States, Dessima Williams, was arrested by Immigration and Naturalization Service agents at Howard last night.]

In addition, 21 persons, including the Rev. Daniel Berrigan, were arrested at a White House gate after blocking it in protest of the Grenada intervention.

"If Ronald Reagan is so interested in saving people from injustice, why didn't he invade South Africa and save the people from apartheid?" Isabel McDonald, a student at American University, asked about 100 who attended an anti-Grenada rally on the central quad of the AU campus.

That noon rally and teach-in sparked more interest than a nearby pumpkin sale, but not much more.

Several students pushed their way through the small crowd, cracking jokes about the gathering or denouncing it as a "commie rally." A few others, members of the Young Americans for Freedom, stopped by to argue with the organizers and to talk up their pro-Grenada rally, set for today.

"Today the enemy is having their say," said Mark Hart, 24, a graduate student in religious studies and a YAF member. "Tomorrow, we will have our say."

Supporters of what was billed as Grenada Liberation Day, said they held "successful programs" at dozens of campuses.

The USA Foundation, which helped organize pro-Grenada events, claimed particularly good turnouts at Penn State University, the University of Wisconsin, the University of Georgia, Marshall University in West Virginia and Idaho State University, according to spokesman Gary Willett.

Organizers of what was called National Student Peace Day, said they had held equally successful anti-Grenada activities, including a forum addressed by Rep. Barney Frank (D-Mass.) at Wellesley College, a forum at Columbia University featuring Rep. Ted Weiss (D-N.Y.) and ex-prime minister of Jamaica Michael Manley, and a march at the University of Colorado in Boulder.

There were also plans last night to protest appearances by Vice President Bush at Syracuse University and U.N. Ambassador Jeane Kirkpatrick at the University of Washington in Seattle, according to Kathy Shulman, a spokeswoman for the coalition of student and youth groups coordinating the Peace Day events.

The AU rally featured Josephine Butler, a candidate for an at-large seat on the D.C. City Council. Butler called it a "sickness" that anyone on campus or in the country would "celebrate the force and might the U.S. put upon less than 100,000 people."

She said the U.S. military build-up costs money that is taken from domestic programs for the poor and for education.

Two brothers, Steve and Peter Jones, performed satirical songs at the rally, attacking Reagan and his policies.

"The problem is not Ronald Reagan's age," said Steve Jones. "I think he was dangerous 20 years ago."