U.S. President Barack Obama extended a rare gesture when he shook hands with Cuban President Raul Castro at a memorial for Nelson Mandela on Tuesday, December 10, in Johannesburg, South Africa, according to a Reuters report.

According to the report, the rare gesture from the two leaders is a reflection of the late former South African president's spirit of reconciliation.

Obama extended his hand to the communist leader when he got up on stage and walk in front of Castro who smiled and also shook the U.S. president's hand.

The only other time that such gesture took place was at the United Nations in 2000 when Fidel Castro, former Cuban president and Raul's brother, shook then-U.S. president Bill Clinton's hand.

However, the handshake did not prevent Obama from extending tough words to world leaders as well. He pointed out that there are leaders who invoked Mandela's fight against oppression, but quash those opposing their leadership at home.

"There are too many of us who happily embrace Madiba's legacy of racial reconciliation, but passionately resist even modest reforms that would challenge chronic poverty and growing inequality," Obama said, who was speaking yards away from Castro and Chinese Vice-President Li Yuanchao, according to the Reuters report.

The U.S. president added that "there are too many leaders who claim solidarity with Madiba's struggle for freedom but do not tolerate dissent from their own people," using Mandela's clan name.

Mandela is revered across the world as a symbol of forgiveness and reconciliation. He fought for the end of apartheid in a country that was ruled by a white minority. In 1993, Mandela was a recipient of the Nobel Peace Prize and shared it with F.W. de Klerk, South Africa's last white president.

"He was more than one of the greatest leaders of our time. He was one of our greatest teachers," U.N. Secretary General Ban Ki-moon told the crowd. "His baobab tree has left deep roots that reach across the planet."