A new US policy on El Salvador?

Is the United States moving toward a new El Salvador policy? That is the essential question emerging from last week's Washington meeting between high US officials and two representatives of the Salvadoran guerrillas.

''Purposeful'' was how Ruben Zamora, one of the Salvadorans, describes the session.

''We each understand each other better, and I think there will be further contact,'' he says. But, like the State Department, he won't give specifics of the Dec. 15 meeting.

The unusual and unexpected meeting has sparked speculation that the Reagan administration may be backing away from its longstanding opposition to negotiations with the guerrillas. The US has been quick to deny such speculation.

But the meeting was clearly a major departure for the Reagan administration. It suggests that the US is trying to open a channel of communication with the guerrillas.

A number of nations, including Mexico, which recognizes the guerrillas, have been urging Washington to do just that. Mexican officials, for example, told US Secretary of State Alexander M. Haig Jr. during his recent visit to Mexico City that the US should adopt ''a policy of recognizing reality in El Salvador.''

Whether these urgings had anything to do with the meeting is not clear. But its importance should not be minimized. It brought together Mr. Zamora and Thomas O. Enders, the assistant secretary of state for Inter-American affairs. Mr. Zamora is a member of the political and diplomatic commission of the Frente Democratico Revolucionario, the Democratic Revolutionary Front, which is the guerrillas' political arm. Mr. Enders is the top State Department official on Latin America.

Others at the session included Everett E. Briggs, Mr. Enders's deputy; Ralph L. Braibanti, El Salvador desk officer in the State Department; and Joseph G. Sullivan of the Inter-American policy planning staff. Francisco Altschul was the other Salvadoran.

The meeting came only a day before the United Nations General Assembly passed a resolution calling on the civilian-military junta to negotiate with the guerrillas.

The junta, which has refused to do so and planned its own elections in March, is unlikely to be persuaded by the UN. Salvadoran President Jose Napoleon Duarte termed the UN resolution ''a sham.''