What did Pope Francis mean when he said "who am I to judge" homosexuals?

It's approaching two years since this happened, but it seems relevant in light of recent events concerning homosexuality. Speaking to reporters on his plane who had asked him about a "gay lobby" in the Vatican, Francis said, "If someone is gay and he searches for the Lord and has good will, who am I to judge? " Clearly the *church* judges their actions (whenever there _are_ actions accompanying the desires). What exactly did he mean by "who am I to judge"?