"Legally, I am still President. My resignation was not considered by the Legislative Assembly.... Even if it was accepted, they also failed to comply with the procedures for constitutional succession, so (Jeanine) Anez proclaimed herself President illegally," Morales tweeted on Thursday.
He said that the law allows him to remain in office until his mandate concludes on January 22, 2020, reports Xinhua news agency.
Morales resigned on November 10 following weeks of opposition protests against his re-election to a fourth term.
Two days later, opposition senator Jeanine Anez assumed the presidency of the Bolivian Senate, which has allowed her to also proclaim herself interim president of the country.
Later, Morales flew to Mexico and then arrived in Argentina on December 12 as both countries offered him refuge.
On Wednesday, Bolivia's attorney-general's office issued the arrest warrant against Morales, accusing him of "sedition, terrorism, and financing terrorism".
"The arrest warrant is unjust, illegal and unconstitutional, because it is not proceeding legally. I am still President and for that reason Bolivian legal procedures must be complied with," Morales said in his Thursday tweet.
Bolivia's interim government said on Thursday that it will approach the UN High Commissioner for Refugees to determine whether refugees like Morales were permitted to engage in politics.
"We are going to consult them on whether it is permissible for refugees to give opinions of a political nature, to undertake political actions that put the stability of the country ... at risk," said Foreign Minister Karen Longaric of the interim government.
Longaric added that the interim government hopes Argentina could help arrest Morales.
( With inputs from IANS )