Livingstone said both parties had exchanged "those things in which they are rich to the mutual benefit of both".
"This will make it cheaper and easier for people to go about their lives and get the most out of London," he was quoted as saying in Australia's The Age newspaper.
But Livingstone's critics slammed the deal as "immoral", asking why one of the world's richest capitals should accept developing world subsidies.
Poor Londoners will get half-price fares
on the city's buses [AP]
Angie Bray, the London Assembly Conservative leader, said the mayor should have requested for financial help from the British treasury instead.
"Most Londoners will reflect that the mayor of one of the richest cities in the world buying popularity off the backs of those in one of the poorest cities in the world beggars belief," she said.
"The spectacle of our mayor, who supposedly believes in social justice, going cap in hand to a dictator with a monstrous human rights record – and who presides over a sizeable portion of people in the direst poverty – to skim off a resource which is needed to relieve such poverty, is morally indefensible."
Livingstone is no stranger to criticism for his diplomacy with countries isolated by the UK and the US, such as Cuba.