Two dozen parents of Riverside Elementary School pupils in Fairfax County agreed last night to ask their PTA to hold another meeting about a kindergarten girl with AIDS in order to explore the possibility of filing suit to prevent her readmission to class.

"That's all we ask, a chance to talk to the other parents," said Betty Malone, who organized the meeting held at a county library. Malone opposes allowing the girl to return to school, contending that it would be unsafe.

The 5-year-old girl was removed from school in November because she has acquired immune deficiency syndrome. The county School Board voted Jan. 2 to allow her to return because of medical assurances that she does not pose a danger to other pupils or teachers. The school PTA sponsored a meeting Jan. 5 at which school officials explained the decision to readmit the child and presented information about AIDS.

Riverside PTA President William Herker said he will bring the parents' requests for a meeting before the PTA board at its meeting tonight. Herker said he believes that "most of the parents are very comfortable with the decision that has been made" and that the parents protesting it are a minority.