A gala benefit concert, with some of the best-known women performers in pop music, is being planned for the United Nations General Assembly on the evening of March 8.

The concert will take place on International Women's Day as the formal opening for several months of concerts and events organized by the International Women's Year.

Income derived from the sale of tickets (at benefit prices) in the 2050-seat General Assembly and from commercial time on television specials projected for later dates in both this country and in Europe will go to UNICEF, which is organizing the concert along with the arts festival board. Tickets for the event are not yet on sale.

According to a spokesman for the United Nations Children's Fund, the following performers have "expressed an interest in participating" without fees (no written contracts have yet been signed): Cher, Ella Fitzgerald, Olivia Newton-John, Shirley MacLaine, Bette Midler, Liza Minnelli, Anne Murray, Dory Previn, Diana Ross, Buffy Sainte-Marie and Mary Travers. Glenda Jackson has been approached to be master of ceremonies.

Joan Baez and Bonnie Raitt, the spokesman said, are more doubtful. Judy Collins, Roberta Flack, Aretha Franklin, Joni Mitchell, Maria Muldaur, Helen Reddy, Linda Ronstadt, Carly Simon and Barbra Streisand have declined invitations.