I am not too well versed in what is going on in Mali, because I have barely studied it but one thing that stands out drastically is that Mali's currency is the
CFA (French Franc).. This is why France wanted Gaddafi so badly. In 2007 Gaddafi said he was going to unite Africa under a new currency, gold. This would have made Africa extremely wealthy, and would have hurt France's power in the region significantly. If you control the currency you control the economy and the government.
I am sure this is a big factor in France's involvement.