In an interview with the Star newspaper published on Wednesday, Malema described Lamola as a "traitor" and a "sellout", who switched allegiance to President Jacob Zuma's camp in exchange for a chance to take over as league president after Mangaung.
In a statement issued on Wednesday afternoon by its spokesperson Khusela Sangoni-Khawe, the league said that Malema's "bloodcurdling remarks are not worthy of a leader".
"Julius Malema should be ashamed that he has failed to show leadership to the youth of South Africa by constructively engaging issues of conflict he perceived. These reports must indeed be a disappointment to the youth who look upon him as a leader of young people of this country and beyond.
"Julius Malema's unfortunate action of resorting to public squabbling and accusations is not befitting the stature with which young people regard our organisation, the ANC Youth League, and hence we will rise to defend anything we view as an unwarranted attack against it, its views and positions," the statement said.
"The ANC Youth League is an organisation far above any individual. It is a fact that the ANC Youth League is not accused of money laundering in any court of law and the deputy president remains correct in distancing the organisation from private issues of individuals regardless of what position they may or may not hold in the organisation," it said.
"The National Executive Committee has no resolution to support individual members of the organisation who appear before court in respect of their personal affairs, neither have we sought to stop members who want to attend in support of Julius in their personal capacity … It is when the movement abrogates upon itself challenges that are not of its making but of individuals, that you begin to build a cult of personality and find the organisation entwined in messes such as The Spear saga and many we have seen in recent days," the statement said.
Malema's outburst came few days after Lamola released a statement warning youth league members against supporting Malema in his upcoming money laundering case.
Meanwhile, former ANC Youth League spin-doctor and national executive committee member Floyd Shivhambu has called for cool heads to prevail between the so-called economic freedom fighters and the league.
Shivhambu, a close ally of Malema called on Lamola and Malema to abandon their petty differences "to ensure an important step forward towards the attainment of economic freedom".
"An immediate threat to the struggle for economic freedom in our lifetime is disunity of the fighting forces and such disunity can be nipped in the bud. As the two most senior commanders in the struggle for economic freedom in our lifetime, both president Julius Malema and deputy president Ronald Lamola carry the responsibility and obligation of this generation to guide all progressive forces towards victory in the war for economic freedom in our lifetime.
"Tactical blunders and mistakes, which include miscommunication, have potential to throw confusion among economic freedom fighters and disorganise the struggle for total economic emancipation. These two leaders of the movement should internalise it within themselves that on their shoulders rest a massive burden to lead the struggle for the emancipation of so many young people who are hopeless and dejected due to problems of the post democratic dispensation," Shivambu said.
He warned that the infighting between youth league leaders ahead of the ANC's crucial elective conference was likely to weaken those who are calling for leadership and policy change.
"The ANC Youth League and the struggle for economic freedom in our lifetime is bigger than all of us and should never be compromised, nor drowned in sounds of tactical differences on what should constitute the change in the 53rd national conference battleground … We need to rise above these differences and unite our people for the common good and avoid playing into the hands of the enemy camp, because the political battles in the ANC are not insignificant," said Shivhambu.