Judge Fernando Andreu said in a court order on Saturday that the group, based in the northeastern Catalan town of Vilanova i la Geltru, was based around a mosque.
Iman Mohamed Samadi gave "radical speeches, particularly at Friday prayers, in which he requested prayers for mujahidins, or for people who had given their lives for the jihad (holy war)".
Samadi also collected funds at the mosque to support the jihad and the group met privately at the mosque at unusual times of the day to avoid being detected, the judge said.
The seven were among 21 arrested this week who Spanish authorities say formed two cells of alleged radical Islamists.
The group was believed to have recruited an Algerian who killed 19 Italians and nine Iraqis when he blew himself up in Iraq in 2003.
Along with Samadi, others sent to prison pending trial were named as Mohamed Mrabet Fahsi, Hassan Mordoude, Mostapha Fawzi Ait Oudriss, Mostapha Es Satty, Mounir Mrabet Fahsi and Abdelhak Boudina.
The seven charged were among
21 arrested this week
Another man, who was not named, was released but ordered to make regular appearances before police.
The rest of those arrested this week may be charged later on Saturday by another judge at Spain's High Court.
One of them, Omar Nakhcha, is thought to have helped three of the suspects in the March 11 Madrid train bombings that killed 191 people, escape Spain.