The blast occurred in the commercial capital's Sidi Moumen area, home to 13 suicide bombers who killed 32 people in
Government security officials said the man had a dispute with the internet cafe's owner.
"We do not know whether the explosion was a suicide bombing or the explosive device went off inadvertently during the dispute," said one official, asking not to be identified.
"The man used to come to view jihadist websites and the dispute was prompted by the internet cafe owner's decision to prevent him this time from viewing such propaganda material," said the official.
Hasan al-Rashedi, Al Jazeera's Moroccan office chief, said it seemed that the bombers were in the cafe to get orders over the internet about a planned attack.
Another man, with the bomber at the time of the blast, fled after the explosion but has now been arrested by police, reports say.
"The man used to come to view jihadist websites and the dispute was prompted by the internet cafe owner's decision to prevent him this time from viewing such propaganda material," one official told Reuters.
"The investigation is continuing and we hope the arrested man will talk and clarify more the matter, including whether the man with the explosives planned a bomb attack elsewhere," said the official.
There was no immediate claim of responsibility by militants for any attack in
One theory is that the man was trying to access websites or email to receive instructions on where to detonate the explosives.
The blast occurred in a slum area of the city that was home to 13 suicide bombers who carried out a series of co-ordinated suicide bombings in 2003 which left 33 people dead.
