The White House announced yesterday that, despite growing criticism, it will ask the Senate to act quickly to confirm Alfred S. Regnery, President Reagan's controversial choice to head the Justice Department's Office of Juvenile Justice and Delinquency Prevention.

The nomination had been on hold for nearly two weeks while the FBI investigated charges by a Madison pediatrician that Regnery poses "a danger to the health needs of our children."

Citing medical ethics, Dr. William Ylitalo refused to comment on his charge except to say that he based his opinion on Regnery's behavior during the 1975 birth of one of his children in Madison, where Regnery then lived. However, Ylitalo talked extensively with the FBI after Regnery waived his right to medical privacy.

"We see no reason, based on the allegations of the doctor, that we should hold up the nomination," said White House counsel Fred F. Fielding after reading the FBI report. He said it has been given to the Senate Judiciary Committee with a recommendation that the panel approve the nomination of Regnery, now serving as the department's acting director. The Senate committee is to consider the nomination today.

Regnery, a former official of Young Americans for Freedom and former aide to Sen. Paul Laxalt (R-Nev.), has been a subject of controversy because of his stated plans to shift the emphasis in the office away from delinquency prevention and toward harsher punishment for juveniles who commit serious crimes.

Meanwhile, The Washington Post has learned that Justice Department officials have blocked a $98,300 grant that was under consideration by Regnery's office after learning that Regnery was to have been paid to write part of the study.

Employes in the office say that Regnery gave his initial approval of the contract for Randall R. Rader, a top aide to Sen. Orrin G. Hatch (R-Utah), to produce a book on the juvenile justice system. According to the contract proposal Regnery was to have been paid $1,000 for writing one chapter.

The proposal, a copy of which was obtained by The Post, indicated that the book was to include several chapters of another Rader book recently published by a firm headed by Regnery's father. Henry Regnery is president of Regnery/Gateway Inc., which published "Criminal Justice Reform," released two weeks ago. Rader was co-editor of that book, which was prepared for the conservative Free Congress Research and Education Foundation.

Regnery, who was attending a meeting in Detroit, did not return telephone calls yesterday. But a department spokesman said that Regnery never approved the grant application formally, and merely forwarded it to the comptroller's office for further review.

But sources in the juvenile justice office said grant applications are not sent on to the comptroller without Regnery's approval. They said that employes in the comptroller's office immediately raised objections about a possible conflict of interest and that Regnery was told that Rader should withdraw the application. It was withdrawn last week.

Rader conceded yesterday that it was a mistake to include Regnery as a recipient of the funds.

"That was my problem. I perhaps should have known better," Rader said. He added that he withdrew the application on his own, however, without any request from Regnery's office.