The Reagan administration, saying it will not tolerate a "double standard" on the issue of human rights, yesterday defended its lifting of two sanctions that had been imposed on Chile, and told Congress to expect "further steps to accord Chile equitable and evenhanded treatment."

While a number of Democratic House members attacked the lifting of the sanctions, John A. Bushnell, acting assistant secretary of state for inter-American affairs, told two House subcommittees that the sanctions, while justified in the aftermath of the 1976 murder here of Chilean diplomat Orlando Letelier, now serve only to damage U.S. commercial and security interests.

Reviewing the Carter administration's policy toward Chile, Bushnell said, the Reagan administration concluded that "this is one place where we were shooting ourselves in the feet and should stop it."

Bushnell testified before the House inter-American affairs and international economic policy subcommittees on the administration's decision to lift two of the sanctions imposed in November 1979 in retaliation for Chile's refusal to extradite three former police officers. The men were indicted in this country in the car-bombing murders of Letelier and an American associate, Ronni Moffitt, on a Washington street in September 1976.

The State Department announced last month that it was lifting the ban on Export-Import Bank credits to Chile for the purchase of U.S.-made goods and was inviting Chile's military government to resume participation in annual joint exercises with U.S. and Latin American naval forces.

That decision, which brought protests from human-rights advocates and those involved in investigating the Letelier murder, has become a focal point in the debate over the shift in American policy away from former president Carter's emphasis on human rights to President Reagan's stress on combatting terrorism. The debate continued yesterday before the two subcommittees, with each side accusing the other of using a "double standard" when dealing with human-rights violations or terrorist activities.

Calling the Letelier murder a clear-cut case of international terrorism, Rep. Thomas R. Harkin (D-Iowa) said the lifting of the sanctions amounted to U.S. acquiescence in Chile's "manifest intention to sponsor, support and protect international terrorists."

"Is there some kind of terrorism this government will support if it is their kind of terrorism?" Harkin asked.

"I don't doubt that in many capitals of the world, tyrants are raising their glasses in celebration of the Reagan administration's apparent response to terrorism" when practiced by an anticommunist military regime such as Chile's, said Rep. Toby Moffett (D-Conn.).

Bushnell testified that despite the Letelier murder, Chile has made important advances in human rights but is the victim of a "blatant double standard" in this area. But henceforth, he said, "the U.S. position is that we will not participate in a dual standard focusing on Latin America and South Africa when countries we know are much grosser [human-rights] violators are never mentioned."

Bushnell did not specify what other steps the administration plans with regard to Chile but said they would be aimed toward reestablishing "normal relations." He said the decision to lift the ban on Export-Import Bank credits now rather than later was affected by pleas from a number of American firms interested in pursuing large projects in Chile.

Despite the lifting of the two sanctions, Bushnell said, the United States has received no assurance from Chile of additional cooperation in the Letelier case.