Prosecutors had asked for eight years for Cherif, who has already spent 17 months in provisional detention.
About a dozen young people from the north of Paris had left France for Iraq, via Syria, in 2003 and 2004. Prosecutors say they went to fight US troops there.
A Paris court had convicted seven of them in 2008, and sentenced them to prison terms of between 18 months and seven years.
Cherif was arrested by the US army in Iraq near Fallujah in 2004, and was held for 19 months in various prisons, including the notorious Abu Ghraib, where he claims he was mistreated.
He was convicted in Baghdad in July 2006 for illegally crossing the border, and sentenced to 15 years in prison. He escaped in March 2007, after an insurgent attack. He turned himself in to French authorities in Syria in February 2008.
Cherif, who converted to Islam in 2003, claims he went to Iraq to support the Iraqi people, and has denied having any links with Al-Qaeda. The prosecution said he went there to join a terrorist network.