A House Foreign Affairs subcommittee, over objections from the Reagan administration, yesterday endorsed new U.S. economic and military sanctions against Chile because of the "marked deterioration" in the human rights situation there.

The action by the human rights and international organizations subcommittee followed a similar endorsement Tuesday by the panel's Western Hemisphere affairs subcommittee. Two more subcommittees are expected to pass soon on the Chile resolution, sponsored by Rep. Ted Weiss (D-N.Y.) and 53 others.

The resolution, calling for "restoration of democracy in Chile," is a strong expression of congressional views, but its recommendations for sanctions would not be binding on the administration.

Among sanctions suggested are U.S. votes against loans and grants to Chile by international financial institutions, and an end to all U.S. military and economic assistance to Chile, including cash sales of military equipment and joint military exercises.

It was learned, meanwhile, that Senate conservatives are seeking to block the nomination of Harry G. Barnes Jr., Secretary of State George P. Shultz's choice to be U.S. ambassador in Santiago.

Senior State Department officials said Barnes, chosen late last year to take the sensitive and high-priority post in Santiago, may well be sent to Venezuela instead.

Such a switch would be a blow to Shultz's policy and prestige, especially if forced on him by conservatives in Congress.

Administration sources acknowledged that strong conservative opposition led by Sen. Jesse Helms (R-N.C.) has persuaded the White House to hold up Barnes' nomination and to consider nominating someone more acceptable to conservatives. Sources close to the conservatives said they have asked the White House to give the job to Thomas Aranda Jr., a Phoenix lawyer now ambassador to Uruguay.

Aranda may be sent to Santiago instead of Barnes, according to the State Department sources, although they said no final decision has been made.

Department specialists on Latin America said that, while such a switch might be a face-saving compromise for Shultz, it would make no sense in policy terms.

They said Barnes is not a specialist on Latin America and was chosen for Santiago because Shultz wants to make clear his concern about Chile by sending someone known to enjoy his confidence. By contrast, they added, Aranda is not regarded as having distinguished himself in Uruguay and is not considered close to Shultz.

As part of a much-discussed policy shift, Shultz had decided to drop Ambassador James Theberge, a political appointee regarded as being close to Chilean leader Augusto Pinochet, and replace him with Barnes, who would be perceived by all factions in Chile as Shultz's direct representative.

Sources familiar with the situation said Helms and his allies suspect that Shultz wants Barnes in Chile as the prelude to a campaign to force Pinochet out of office. In addition, the sources said, the opponents charge that Barnes, who served as director general of the Foreign Service during the Carter administration, favored liberals over conservatives in appointments to foreign-policy posts.

These sources said conservatives know that they cannot muster votes to block Barnes from being confirmed by the Senate. Instead, they concentrated on trying to persuade such key White House officials as chief of staff Donald T. Regan and national security affairs adviser Robert C. McFarlane that a conservative political appointee such as Aranda would be a more reliable guardian against leftist threats to U.S. interests in Chile.

Deputy Assistant Secretary of State James H. Michel told the human rights panel yesterday that he opposes passage of the Weiss resolution. He said "the situation is far too complex and our interests too important" in Chile for "rigid positions" to be desirable or effective.

Michel said the administration shares the objective of moving Chile toward restoration of democracy. But he said the resolution, while it "may be attractive from a domestic political viewpoint," would have "little bearing on supporting the return to democracy."

State Department sources said the probable effect of congressional passage of the Weiss resolution would be to harden Pincohet's attitude. The Chilean leader is considered nearly intractable on human-rights and political issues.

Michel suggested in his testimony that U.S. access to Pinochet, for the purpose of making the case for reforms, could be damaged by passage of the resolution.