Based on other statements Francis has made, I don't think he opposes free enterprise. I do think, though, that he is highly cautious about unregulated, unbridled capitalism. I think the "god of money" to which he refers is greed, which inevitably leads to a violation of human dignity.

For Christians, making a "god" of anything other than Our Lord and Creator is a violation of the first commandment. Idolatry isn't only harmful under certain conditions. It is always harmful.