"Lalu is paying the price for his uncompromising stance against the BJP. Had he compromised, his detractors would have been comparing him to Raja Harishchandra," the former Deputy CM quipped.
A bail plea will also be moved in the high court, Tejashwi told a press conference at the residence of his mother and former Bihar Chief Minister Rabri Devi.
The special CBI court on Saturday sentenced RJD chief Lalu to three-and-a-half years in jail and imposed a fine of Rs 10 lakh on him in the fodder scam case relating to fraudulent withdrawal of Rs 8.9 million from the Deoghar Treasury 21 years ago.
"Lalu is not the name of a person but of an ideology. We, his followers, will not be cowed down," said the 28-year-old Leader of Opposition in the state assembly.
Tejashwi, against whom a contempt notice has been issued by the CBI court for criticising its December 23 judgement whereby Lalu was convicted, said, "The lower court has pronounced its judgement which we respect. We have full faith in judiciary".
"We will study the judgement and then decide on what legal options to exercise," he added.
If the quantum of sentence was less than three years, the bail plea would have been moved before the trial court itself, he said.
"Since that does not appear to be the case, we will have to do so before the high court where we will also appeal against the conviction."
Tejashwi also charged Chief Minister Nitish Kumar and the BJP with "conspiring against Lalu, whose immense mass appeal and willingness to courageously take on communal forces have always left his detractors insecure".
Tejaswi was speaking after an RJD meeting, at Rabri Devi's bungalow, which was attended by senior party leaders including state chief Ramchandra Purve, Jagdanand Singh and others on the future course of action of the party.
During the meeting, Jagdanand Singh read message of Lalu Prasad written to partymen before going to the Ranchi jail after the conviction on December 23.
Tejashwi said the party would go to people after makarsankranti to make them aware of the "conspiracy" hatched by Nitish Kumar and the BJP against Lalu.
He also dismissed suggestions the party may disintegrate with its top leader being behind the bars, saying "The more we are harassed, the stronger will be the public support in our favour. Lalu resides in the people's hearts".
"He is in jail, yet everybody is talking about him. The only reason is that the people of Bihar are with us and this scares our opponents," he added.
Yadav also took potshots at the ruling JD(U)-BJP combine, saying, "Let the double engine do something for the betterment of Bihar. They should set their own house in order instead of wasting their energy on the future of RJD".