Ottawa — Canada suddenly finds itself in a quandary over Central America. Although Ottawa continues to express its deep concern about the ''escalating military confrontation'' in the area, it now appears equally worried about leftist guerrilla advances in El Salvador and the ''tendency toward authoritarianism'' in Sandinista Nicaragua.
In the process, moreover, Canada is edging closer to United States views on Central America.
It was not always so. As recently as last April, Prime Minister Pierre Trudeau was much more sanguine about Nicaragua and about the guerrilla activities in El Salvador than Canadian officials are today. He also was sharply accusing Washington of meddling in the internal affairs of Central American countries.
Now, there are clear hints that Canada is pulling back from its earlier strong support of Sandinista Nicaragua - a policy shift that appears to stem from Canadian diplomatic reports which suggest growing leftist militancy in Nicaragua and a movement away from promised political pluralism.
Canadian spokesmen are currently choosing their words on Central America carefully. This is particularly evident when it comes to comment on US policy toward the troubled region.
''We fully appreciate the dilemma that is facing the United States,'' says External Affairs Minister Allan J. MacEachen, ''as it seeks to respond to these explosive events in a region of strategic importance to US interests.''
In particular, Canada is tending toward at least acquiescence in Washington's military assistance program for El Salvador. Mr. MacEachen indicated that Ottawa , regarding the government of El Salvador as legitimate, saw nothing wrong in such a government seeking ''support from other countries, such as the United States, to defend itself.''
Such military aid goes against the grain of Canada's traditional neutrality and its support for peace initiatives to settle disputes. And Ottawa's position is far short of outright support for the US military aid effort.
But it seems to some Canadians to give legitimacy to that effort - and certainly is far from the stand that many individual Canadians embrace.