She is a brooding, "unrecognised force" in the White House, a new book claims; in frequent conflict with her husband's aides and quick to impose her disapproving views on the presidential staff.

Not so, according to Michelle Obama, who spoke out yesterday to dismiss the allegations, saying this was merely the latest attempt to paint her as "some kind of angry black woman".

The first lady chose to speak out following the publication of The Obamas, an unauthorised biography of the president and his wife by the New York Times reporter Jodi Kantor.

The book blames a "deeply frustrated and insecure" Mrs Obama for frequent tension within her husband's inner circle, and details ill-tempered run-ins with his former chief of staff Rahm Emanuel and former press secretary Robert Gibbs.

But in an interview with CBS News, Mrs Obama said she and Emanuel had "never had a cross word". "I don't have conversations with my husband's staff. I don't go to the meetings. Our staffs work together really well. So if it were ever an issue it would go through that channel anyway.

"I guess it's just more interesting to imagine this conflicted situation here," she said. "That's been an image people have tried to paint of me since the day Barack announced, that I'm some kind of angry black woman."

Kantor's book, which she says is based on interviews with 33 White House staffers, describes a "grim situation" in early 2010, after the Democrats lost Edward Kennedy's seat on the Senate to the Republicans, with "a president whose agenda had hit the rocks, a first lady who disapproved of the turn the White House had taken, and a chief of staff who chafed against her influence".

It claims Mrs Obama, whose husband will seek re-election in November, let it be known she felt the administration's "rudder isn't set right", to which Emanuel reacted "indignantly", and that she was furious when he promised her presence at an event without consulting her, responding by refusing to commit to campaigning for the midterm elections later that year. Emanuel left his position in September 2010 and was later elected mayor of Chicago. Mrs Obama said he and his wife were "some of our dearest friends".

Asked by the CBS reporter Gayle King if she had felt frustrated or unhappy in her position, she said: "I love this job. It has been a privilege from day one … If there's any anxiety that I feel it's because I want to make sure that my girls come out of this the other end whole. But me and Barack, we're grownups, all the ups and downs, we take it on."

On another occasion detailed in the book, Gibbs is alleged to have "cursed" the first lady, after another staffer said she had been unhappy with his response to a claim in a book, denied by Mrs Obama, that she had told Carla Bruni-Sarkozy that living in the White House was hell.

Asked about the incident, Mrs Obama said: "I'm sure we could go day to day and find the things people wish they didn't say to each other. People stumble, people make mistakes." Gibbs, she said, was "a trusted adviser … and remains so. He's been a good friend."

Mrs Obama had initially "bristled" at the confinements of her new role, according to Kantor, having given up her own career during her husband's campaign. An early plan to return to the family home in Chicago had to be abandoned when the security demands of their position made it impractical.

Kantor writes that she also "wanted everything to be flawless and sophisticated" as, according to a former aide, she felt "everyone was waiting for a black woman to make a mistake". But, she writes, she grew into her role, becoming more confident and popular as her husband's political agenda faltered at times.

Speaking to King, Mrs Obama did not dispute that her time in the office had been a "learning curve", particularly when it came to issues she has campaigned on, such as childhood obesity. "You start out with these ideas but you have no idea whether what you want to do with them is going to go anywhere. So then you're a little hesitant, you're careful, you're doing more planning and learning than you are doing."

The first lady had agreed to the interview before Christmas, King said, and she spoke with one eye on her husband's re-election campaign, saying: "If I take my 'Michelle-the-wife' hat off, we need this man in office, and he's doing a phenomenal job." Asked about those who felt disappointed by his presidency so far, she said: "They just don't know. This campaign is going to be about making sure people understand about what's been accomplished, I think people are confused … about how much has been accomplished, but that's what you do in a campaign."