Olivier Morice, a lawyer for civil parties to the case, said: "This is an important and historic decision because it is the first time that Scientology has been found guilty of involvement in organised fraud."
Ian Haworth, general secretary of the Cult Information centre in the UK, told Al Jazeera he was "delighted" by the verdict.
"They're flagging it up as a problem as far as they're concerned and it has a criminal record now in that country ... and I think it's a way of warning the public yet again".
But Eric Roux, a Celebrity Centre spokesman, said after the ruling: "Religious freedom is in danger in this country." He urged France to "recognise the legality of the Church of Scientology".
"It is very regrettable that the law quietly changed before the trial"
Georges Fenech, head of the Inter-ministerial Unit to Monitor and Fight Cults
Patrick Maisonneuve, a lawyer for Scientology's French operations, said he would appeal, but added "the most important thing is that this association can continue to exercise its activities".
There had been expectations during the trial that the court could order the group to be banned in France, but a change in the law earlier this year meant the option was ruled out.
Under the change, which has since been reversed, judges were barred from dissolving an organisation convicted of fraud.
Georges Fenech, head of the Inter-ministerial Unit to Monitor and Fight Cults, told France 24: "It is very regrettable that the law quietly changed before the trial.
"The system has now been put in place by parliament and it is certain that, in the future, if new offences are committed, a ban could eventually be pronounced."
The case, which began on May 25, was brought by two former members who said they were cajoled into spending 21,000 euros ($31,183) and 49,500 euros on personality tests, vitamin cures, sauna sessions and "purification packs".
Scientology has faced numerous setbacks in France, with members convicted of fraud in Lyon in 1997 and Marseille in 1999.
In 2002, a court fined it for violating privacy laws and said it could be dissolved if involved in similar cases. Scientology says it has gone to court in many countries to uphold the right to freedom of religion.