Security has been tight around the high-profile trial
Aeurobui Beandali and three other Algerian nationals are standing trial in the German city of Frankfurt on charges of planning to bomb a public square during the Christmas season in 2000.
But Mr Beandali said the neither the square nor the cathedral that stands there were targets of the planned attack, but one of the city's synagogues.
He said the plot, which was foiled by German police, was intended to send a message to both France and Israel and to destabilise relations between the two countries.
It was scheduled for January or February of 2001, he said.
He also insisted that the group had not intended to kill anyone, adding that this would "not have been compatible with Islam".
'Media trial'
The plot was foiled after German police, acting on a tip-off from foreign intelligence, raided flats in Frankfurt.
They found bomb-making equipment, weapons and an amateur video of the Strasbourg market and cathedral on which a voice could be heard saying: "You're all going to go to hell, God willing."
Mr Beandali said the video of the cathedral had been recorded by mistake as one of his accomplices had mistaken it for the synagogue.
German prosecutors believe that the four defendants, as well as a fifth man also on trial, trained at Osama Bin Laden's terrorist camps between 1998 and 2000 and in late 2000 set up the first fully functioning al-Qaeda cell in Germany.
All five are charged with membership of a terrorist organisation.
Mr Beandali told the court that while he had trained at a military camp in Afghanistan for nine months, the training had "nothing to do with al-Qaeda or Osama Bin Laden".
He said he had received tuition at a private school which he had paid for himself.
During the first day of hearings on 16 April, Mr Beandali's lawyer read a statement in which he protested against what he called a media trial which linked him to the 11 September terrorist attacks against the United States.