Jerome Corsi, who wrote The Obama Nation: Leftist Politics and the Cult of Personality, was picked up by police for not having a work permit, said Carlos Maluta.
Corsi had been scheduled to launch his book on Tuesday in Kenya, where the Democratic presidential candidate is hugely popular.
Mr Obama’s late father, whom he barely knew, was a Kenyan economist and the candidate is considered by many Kenyans as a native son. Minibuses are emblazoned with his picture and vendors sell T-shirts bearing his image.
Mr Obama was born in Hawaii, where he spent most of his childhood raised by his mother, a white American from Kansas.
Corsi’s book claims the Illinois senator is a dangerous, radical candidate for president. It claims falsely that he was raised a Muslim and attended a radical black church.
Mr Obama is a Christian who attended Trinity United Church of Christ in Chicago.
According to a statement announcing Corsi’s visit, he arrived in Kenya last week at the invitation of Christian missionaries concerned about the rise of Islam.