Babies kissed her, toddlers hugged her and one 5-year-old literally knocked her off her feet.

"That's all right. I thought you were being affectionate," Nancy Reagan reassured the youngster named Brian as she picked herself up off the floor. "I was kind of perched," she said of the crouched position she had taken to look him and other small fry in the eye.

The first lady was making a visit yesterday to St. Ann's Infant and Maternity Home in Hyattsville to see her favorite special project, the federally funded Foster Grandparent Program (FGP), one of a handful of programs in any agency that isn't falling under the Stockman-Reagan budget ax.

In fact, the program, which Nancy Reagan has supported since her husband was governor of California, will get a $1.75 million budget recommended by former president Carter.

The first lady disavowed any responsibility for the proposed FGP budget increase, however.

"I had nothing to do with things like that. I don't get into that at all," she told a reporter.

A month ago, when announcing that the grandparent program would continue to be her special cause, she was asked whether she would let her husband cut it out of his then still-unannounced budget. It wasn't a press conference, she reminded her questioner, "but no, I won't. Nor would he want to."

Yesterday, Jack Kenyon, chief of the program, said the first lady had made it "quite clear that it is not her intent to attempt to increase federal appropriations in respect to the program." On the other hand, Kenyon said, "one would expect an answer having to do with the first lady's interest" as one reason why the program wasn't cut.

"We feel the primary thing she will be able to do is to encourage private-sector involvement," said Kenyon. He added that this week the first lady filmed 60 public-service announcement on foster grandparents to be aired over some 900 major television outlets in May, which has been designated Older American Month.

At the 121-year-old home, operated by the Daughters of Charity of St. Vincent de Paul, which offers short-term care to approximately 70 unwanted and neglected youngsters, there were 10 foster grandparents working with infants and toddlers. They are among 65 elderly persons serving at five volunteer stations sponsored by Prince George's County's department of aging.

"We'd wear out a dozen rocking chairs if we didn't have these babies," said Martha McDaniel one of the grandparents receiving $2 per hour, 20 hours a week, to provide what Jack Kenyon called "the warmth of a caring human" to children who might not otherwise experience it.

The first lady and her tiny new friends seemed to get along famously. One 8-month-old discovered how to kiss Nancy Reagan's cheek, then cried when she told him goodbye. Another refused to kiss her ("the fellow upstairs gave me lots of kisses," the first lady coaxed) but gave her a present of framed handprints.

"I guess you can remember when you took your own children's fingerprints, can't you?" a foster grandmother asked.

"Yes, a long time ago. I look at these children and wonder, where did it all go?" Mrs. Reagan replied.

The outing to St. Ann's, which started the grandparent program last October, came about, according to Kenyon, after it was suggested to the White House by Washington Star columnist Mary McGrory, a frequent volunteer at the home.

"Mary, you've just lost one of your children," the first lady said as she was escorted to the door by 4-year-old Lyshawn, who gave every indication that she would gladly accompany Mrs. Reagan to the White House.

Waiting in the lobby was another tot.

"I gotta go to the bathroom," he told the first lady.

"Well, that happens," she said.