Pope Benedict XVI has urged Cubans to build an "open and renewed society", at the start of the first papal visit to the communist-run country in 14 years.
At a Mass in front of some 200,000 people in the eastern city of Santiago, he called for a "renewed society".
The Pontiff was welcomed by President Raul Castro who said the country enjoyed good relations with the Church.
His visit marks the 400th anniversary of Cuba's patron saint, the Virgin of Charity of El Cobre.
The icon - also known as the Mambisa Virgin - was found floating in a bay in 1612 by fishermen and was revered by Cuba's independence heroes.
"I carry in my heart the just aspirations and legitimate desires of all Cubans, wherever they may be, their sufferings and their joys, their concerns and their noblest desires," he said.
He added that he was convinced that the country "at this moment of particular importance in its history" was "looking to the future" and "striving to renew and broaden its horizons".
President Castro was seated in the front row of the Mass in Cuba's second largest city as believers sang hymns and prayed in Santiago's Revolution Square.
The Pope appealed to the audience to reinvigorate their faith "that you may strive to build a renewed and open society, a better society, one more worthy of humanity".
Before the Mass, one man was arrested after shouting: "Down with communism". Others in the audience booed him for spoiling the atmosphere and shouted: "Cuba, Cuba, Cuba".
Ahead of his visit, Pope Benedict had suggested Cuba's Marxist structure "no longer corresponds to reality" and called for the adoption of a "new model".
But on his arrival, he recognised Cuba's efforts to "renew and broaden its horizons".
In his speech at the airport, President Castro said socialist Cuba allowed full freedom of religion and enjoyed good relations with the Catholic Church.
He said Cuba shared the Pope's concerns over global poverty, inequality and environmental destruction.
And he stressed that Cuba was determined to defend its independence in the face of the US embargo.
Both leaders looked back to the visit by the late Pope John Paul II 14 years ago, which Pope Benedict said "was like a gentle breeze that gave new strength to the Church in Cuba".
Observers say relations between Church and state have warmed in Cuba in recent years.
Raul Castro has accepted the Church's mediation on issues such as political prisoners, recognising its position as the most influential organisation outside the communist government.
The Pope's visit is seen as an effort to further improve relations and increase the role of the church in Cuban society at a time of rapid change.
The Pope is expected to travel to Havana later for private talks with President Castro and will celebrate Mass in the capital's Revolution Square on Wednesday.
Church officials have said there is no time in his schedule to meet dissidents.
Opposition groups say dozens of dissidents were detained ahead of the visit, and others were prevented from attending the service in Santiago.
Pope Benedict's trip to Cuba follows a visit to Mexico, where he celebrated a huge open-air Mass at the Christ the King monument in the central city of Silao.
He urged the 500,000 Catholics gathered for the sermon to look to their faith in response to poverty and crime and to reject violence and revenge.