Tejashwi termed the CBI's FIR against him as "political conspiracy" and "vendetta" by the BJP and RSS.
“The FIR by the CBI and all other allegations are results of political vendetta. They are politically motivated by the BJP and RSS as a conspiracy to defame and weaken the Grand Alliance," he said.
"The Centre wants to muzzle the voice of the Opposition. Hence, it's targeting leaders of other parties," he added.
Tejashwi reiterated he was never asked to resign by Nitish Kumar.
"I am working towards Nitish Kumar's agenda of RSS-free India. Why would I even think about resigning when I was never asked to?" he said.
"Today the allegations are on me, tomorrow it could be on Nitish ji. We need to demolish the root from where conspiracy is being hatched," the RJD leader added.
He said the Centre is following Hitler's dictatorial approach and want no Opposition in the nation.
"We need to unite and eradicate such forces," he said.
The ruling Grand Alliance, comprising JDU, RJD and Congress, is headed by Nitish Kumar.
He said that since he became Deputy Chief Minister there have been no corruption allegations against him.
Tejashwi has maintained that all is well as long as the alliance with JDU is concerned.
Earlier in the day, RJD chief Lalu Prasad also ruled out resignation of his son, who is embroiled in corruption charges.
Bihar has been in the grip of a political crisis after the CBI registered a case against Tejashwi in a benami property case and also raided his premises earlier this month.