"As a French guy I wish they are going to win the World Cup, but I think it will be difficult because you have teams who are very strong - Spain, Germany, Brazil," the former Arsenal man said.
"In France everyone expects them to get to the semi-final, so I hope they will do something well.
'We have some good young players. They are very young and very talented and they can make the difference, but the problem is that if we play against a strong team we will be in trouble."
Gallas played 84 times for the French national team and started in the World Cup final in 2006 in which his side lost out to Italy on penalties.
"We will be in trouble because we need to be more strong," Gallas continued.
"We have to have more players who are going to shout on the pitch when you do not play well and at the moment we do not have that type of player.
"So I hope before the World Cup starts the manager will speak with the players and explain to them what they have to do."