Pope Francis gave an unexpected twist to the annual pontifical appeal for peace on Sunday when he used it to denounce "greed looking for easy gain".

In his Urbi et Orbi address, which translates as "to the city [of Rome] and to the world", the pope – who has sought to make himself the tribune of the poor, disabled and disadvantaged – appeared to put uncaring capitalism in the same category as the armed conflicts his predecessors have traditionally, and forlornly, deplored on Easter Day.

Since being elected on 13 March, Francis has repeatedly stressed concern for the poor and others on the margins of society, and he returned to what is clearly emerging as the central theme of his papacy on Sunday. He said he wanted his Easter message of hope and resurrection "to go out to every house and every family, especially where the suffering is greatest, in hospitals [and] in prisons".

Last week, the pope visited a youth detention centre in Rome where he washed the feet of 12 inmates as part of the traditional rite representing Jesus's final act of humility to his disciples.

Francis's denunciation of greed came after he moved among the crowd in St Peter's Square in the popemobile. He kissed babies and children, held a severely disabled young man in his arms and accepted the gift of a football shirt of his favourite team, Argentina's San Lorenzo "Saints". His longest stop was for a disabled child who was lifted into the popemobile and whom he hugged and kissed repeatedly.

According to the Vatican's estimate, some 250,000 people crammed into the square and the broad avenue that stretches away from the Vatican to the river Tiber for the pope's first Easter Sunday mass. By the time Francis, wearing cream-coloured vestments, climbed aboard the open and unprotected Mercedes pontiff-carrier, the square in front of Michelangelo's basilica was a sea of colour.

In addition to the spring flowers on either side of the shallow steps down which the popemobile bumped into the square, there were the flags of countries from Albania to Zambia. The light blue, white and gold of Argentina's flag was well represented and the pope's face lit up in recognition every time he identified a group of his compatriots in the jubilant crowd of tourists, pilgrims and Romans.

In the final event of the gruelling timetable that Easter sets for the leaders of the Roman Catholic church, the 76-year-old Francis's voice occasionally sounded weak. He was, however, visibly energised by his tour of the square and his delivery of the Urbi et Orbi address was forceful and at times impassioned.

He appealed for peace in the Middle East, saying that the conflict between the Israelis and Palestinians had "lasted all too long" and called for an end to violence in Iraq and "dear Syria", the birthplace of Gregory III, the last pope from a non-European country. Francis also urged peace in Africa, specifically citing Mali, Nigeria, the Democratic Republic of Congo, the Central African Republic and Nigeria. He also made a special call for an end to the standoff on the Korean peninsula.

He ended his address by calling, with growing intensity, for "peace in the whole world, still divided by greed looking for easy gain, wounded by the selfishness which threatens human life and the family, selfishness that continues in human trafficking, the most extensive form of slavery in this 21st century. Peace to the whole world, torn apart by violence linked to drug trafficking and by the iniquitous exploitation of natural resources".