Pope Francis has said homosexuals should not be judged or marginalised and should be integrated into society.
In an interview while returning from a visit to Brazil, Pope Francis also said the Catholic Church's ban on women priests was definitive.
However, the pontiff did add that he would like women to have more leadership roles in administration and pastoral activities.
Pope Francis defended homosexuals from discrimination in what was his first news conference since being elected in March.
He also referred to the Catholic Church's universal Catechism, which says that while homosexual orientation is not sinful homosexual acts are.
"If a person is gay and seeks God and has good will, who am I to judge him?" the Pope said.
"The Catechism of the Catholic Church explains this very well. It says they should not be marginalised because of this (orientation) but that they must be integrated into society," he said, speaking in Italian.
"The problem is not having this orientation. We must be brothers. The problem is lobbying by this orientation, or lobbies of greedy people, political lobbies, Masonic lobbies, so many lobbies. This is the worse problem."
Addressing the issue of women priests, the Pope said: "The church has spoken and says 'no' ... that door is closed."
It was the first time he had spoken in public on the subject.
He said: "We cannot limit the role of women in the church to altar girls or the president of a charity, there must be more.
"But with regards to the ordination of women, the church has spoken and says no. Pope John Paul said so with a formula that was definitive. That door is closed."
The church teaches that it cannot ordain women because Jesus willingly chose only men as his apostles. Advocates of a female priesthood say he was acting according to the customs of his times.
Many in the church, even those who oppose a female priesthood, say women should be given leadership roles in the church and the Vatican administration.
In the same interview, the pontiff also said that the troubled Vatican bank must become "honest and transparent" and that he will listen to the advice of a commission he has set up on whether it can be reformed or shut down altogether.
The Pope made the comments on the scandal-hit bank in an 80-minute meeting with reporters on board his plane shortly after leaving Brazil at the end of his first international visit.
The Pope arrived back in Rome today after a triumphant week-long tour of Brazil, which finished with a huge gathering on Rio de Janeiro's famed Copacabana beach, which is estimated to have attracted more than 3 million people.