Vilsack's statement came hours after the Obama administration formally apologized to Shirley Sherrod, who was fired Monday over comments taken out of context.
"On behalf of our administration, I offer an apology," White House Press Secretary Robert Gibbs said during Wednesday's daily briefing.
Gibbs acknowledged that the administration had not seen a full tape of Sherrod's comments prior to Tuesday evening.
"Look, a disservice was done, an apology is owed," he said. "That's what we've done."
A conservative Web site had posted a video of Sherrod, who is black, in which she appeared to be talking about her past hesitancy in dealing with white farmers but was in fact explaining how she overcame her own race-based dispositions.
Vilsack said Wednesday he contacted Sherrod to apologize and told her he was "sorry for the pain this caused her and her family and friends."
"I reacted too quickly," he said. "I should have taken the time to listen and learn."
Vilsack said he and Sherrod discussed "a unique opportunity at USDA."
"With all that she has seen, endured and accomplished, it would be invaluable to have her experience, commitment and record of service at USDA," he said. "I hope she considers staying with the department."
Sherrod told CNN Wednesday evening she had not seen the offer so she has not decided whether to accept it.
"(Vilsack) mentioned something in civil rights with the office of outreach," she said. "I told him I needed time to think about it."
Asked whether she believes President Barack Obama owes her an apology, Sherrod said: "I firmly believe that, if not the president someone there at the White House as involved in that. It would be great to talk to the president but I would not insist on an apology from him."