Sara Jane Moore told NBC's "Today" that she now realizes that her actions were "wrong ... a serious error."
The appearance was Moore's first TV interview since she was released on parole in late 2007, NBC said.
In September 1975, Moore, then around 45, fired on Ford as he waved to a crowd in San Francisco. A man near her knocked the pistol out of her hand and the shot went astray. It was the second failed attempt on Ford's life in less than three weeks.
Moore was sentenced to life in prison but released on parole in December 2007. She has lived in an undisclosed location since then.
It was during the long years in prison, she said, that "gradually I began to realize that I had let myself be used. ... I definitely think that it was wrong. I think I was misled. I think I was mistaken. I think I made a serious error."
Moore, who had been loosely associated with leftist groups in California, said she "wasn't prepared" for the things she learned about the extent of poverty and other problems.
"It was a time that people don't remember. You know, we had a war ... the Vietnam War, you became - I became - immersed in it," Moore said Thursday.
"We were saying the country needed to change. The only way it was going to change was a violent revolution. I genuinely thought that (shooting Ford) might trigger that new revolution in this country."
On politics, she said she now knows she was hearing only one side of the story. "We thought San Francisco was the world, and it wasn't."
Asked by NBC's Matt Lauer why she was doing the interview now, she said, "I think that one gets tired of being thought of as a kook, a monster, an alien, something like that. ... There has been a lot of curiosity. I thought, OK, let's do it."
As for the people in the town where she's now living, who would learn about her past through the interview, "I hope they're OK with it."