President Carter has turned down requests from the Congress-woman's Caucus that he designate Friday as Women's Equality Day, Rep. Margaret M. Heckler (R-Mass.) said yesterday.

Heckler, who with Rep. ELizabeth Holtzman (D.N.Y.) chairs the women's caucus, said she was astonished at Carter's regusal to issue the proclamation as his predecessors have done annually since 1972.

She called it "a most insensitive and unnecessary slight" and urged him to reconsider.

Friday marks the 57the anniversary of the adoption of the 19th Amendment, which gave women the right to vote.

This year, Heckler noted, more than 70 groups will march down Pennsylvanian Avenue to the White House on Friday in honor of the late suffragette Alice Paul and to dramatize the group's support for the Equal Rights Amendment.

Carter has been invited to meet with the marchers and apparently will do so. Heckler said. The caucus was notified of Carter's decision by William M. Nichols, general counsel for the executive office of the President in the Office of Management and Budget. Nichols said, in effect, that the cause wasn't significant enough.

"As I am sure you can appreciate the President receives numerous requests for issuance of commemorative proclamations," Nichols said. "There simply are not enough days, weeks and months in the year to accommodate them."

Heckler noted, however, that since taking office, Carter has issued proclamations for such events as World Trade Week. Armed Services Day, Pan American Day, Pan American Week, Black Press Day, National Farm Safety Week. Order Americans Month, Red Cross Month and Small Business Month.