"The calls for citizens to spoil their votes are blasphemous to the [cause] Madiba and other true struggle stalwarts stood for," the youth league said in a statement on Sunday.
"We call on young people to defend the democratic breakthrough of 1994 and safeguard the rule of South Africa by its majority citizens by voting ANC on May 7 2014."
It rejected former ANC activist and government minister Ronnie Kasrils' call to not vote for the ANC.
"To us as young people of the ANC, the Rivonia trial speech by Madiba is so powerful and does reflect the high-value our freedom and democracy cost our fore-fathers," said league spokesperson Bandile Masuku.
It recalled that on April 20 1964, Mandela, facing a possible death sentence with his co-defendents delivered his famous speech in which he said: "I have fought against white domination. I have fought against black domination.
"I have cherished the ideal of a democratic and free society in which all persons live together in harmony and with equal opportunities. It is an ideal for which I am prepared to die."
Lawyer and friend George Bizos said Mandela heeded his advice and added the words. "But if needs be", to this part of his speech.
The league felt that Mandela's use of the singular form when addressing the judge, indicated the value of self-sacrifice.
Mandela, Walter Sisulu, Ahmed Kathrada, Govan Mbeki, Denis Goldberg, Raymond Mhlaba, Andrew Mlangeni and Elias Motsoaledi were convicted of sabotage and sentenced to life imprisonment.
The Nelson Mandela Centre of Memory said Mandela signed the speech and dated it April 1964 and gave it to Sylvia Neame, a political activist and the partner, at the time, of Kathrada.
She was arrested in August 1964 and put on trial with advocate Bram Fischer and 10 others.
In April 1965 they were convicted and sentenced. Neame was sentenced to four years (two years to run concurrently). She was released from prison in 1967 and went into exile.
After he was released from prison she gave the signed copy of the speech to Kathrada who donated it to the centre.
Mandela died on December 5 2013 at the age of 95 at his home in Houghton, Johannesburg. – Sapa