Four other people were injured in the Sunday night blast, including the dead man's companion, who was hospitalized with burns and an injury to the throat, said Ministry spokesman Abderrahman Achour.
Authorities, uncertain about the circumstances of the blast in a Casablanca slum, held off labeling it a suicide bombing, Achour said in a telephone interview with The Associated Press.
Police were not immediately able to identify the dead man, who was not carrying an ID card. His companion identified himself as Said Jokia, but he, too, was not carrying official identity papers, the Ministry spokesman said.
According to the MAP news agency, two men entered the cafe Sunday seeking access to terrorist Web sites. When the owner's son forbid them from doing so, one of the men suddenly blew himself up, MAP reported, citing the Surete Nationale police.
The injured companion fled the cafe but was later arrested. He was taken to Mohamed V Hospital in Casablanca, the Ministry spokesman said, adding that due to the throat injury police questioning was limited.
A series of near simultaneous suicide bombings that killed 45 people, including a dozen bombers, took place in Casablanca in 2003. Since then, this Muslim North African country has made hundreds of arrests and has been scouring the country for Islamic extremists.