Cardinal Kurt Koch, who leads ecumenical relations for the Vatican, has been speaking after an interfaith meeting held by Cambridge University's Woolf Institute and attended by senior Catholic and Jewish leaders.
It is understood the gathering discussed a recent report by the Pontifical Council for Promoting Christian Unity about the Church's relationship with the Jewish faith.
Quoted in the Daily Telegraph newspaper, Cardinal Kurt Koch, said: "We have a mission to convert Muslims to Christianity. We have a mission to convert all non-Christian religions' people [except] Judaism."
He also urged Christians to view Judaism as a "mother" - despite key differences between the two faiths - and said they have a unique relationship, unlike the third Abraham religion, Islam.
Speaking about the Vatican's position on evangelism, Cardinal Koch added missionaries in the Roman Catholic Church should be reaching out to everyone, who said Jews are exempt because they are God's "chosen".
In the past Pope Francis has said everybody is a child of God.