"It is a character assassination campaign designed to achieve political ends," he said during a briefing on collective bargaining to the South African Clothing and Textile Workers Union (Sactwu).
Vavi hinted that he was being targeted because of his criticism of government but said he was merely the public face of concerns voiced by Cosatu members.
The Mail & Guardian reported recently that the Congress of South African Trade Unions' (Cosatu) central executive committee called for Vavi to be investigated for alleged corruption in the acquisition of Cosatu's new headquarters.
Vavi has denied the allegations and vowed to resign if they were proven to be true.
"I will walk away because it will mean that Cosatu will never again champion the fight against corruption because its own leaders are corrupt, then I walk away comrades, good-bye," he reiterated on Saturday.
"I must tell you that I am stronger personally and not disturbed at all by [these] faceless and spineless people who, under cover of being media sources, are running a media campaign."
Joking that some leaders had traded their principles for sports cars, he said: "Fold the campaign, the congress is over. Workers have elected their own leader and you can't want to change that".
"I know the real reason why these sources are running this campaign is that they want all of us to look the same … [but] I would rather live the life of a beggar than to lose my integrity."
Vavi said the reports threatened to detract from Cosatu's fight for better wages which he vowed the 2.2-million-member organisation intensify at its conference on collective bargaining later this month.
He said solidarity in the labour movement was under sustained attack from employers like clothing factory owners in KwaZulu-Natal who paid machinists R278 a week.
He pointed out that this was less than half the new minimum wage secured by farm workers.
"We want more collective bargaining, not less. We want more extension of agreements and not less because we want to rely on the strength of us … not the mercy of the employers.
"We want collective bargaining to begin to be collective bargaining, not collective begging that the employers are always gunning for." – Sapa.