"The party's chairman has said in public a lot of things, both true and untrue, about me. He cited me as saying what I had never said about the Liberal Movement. Therefore, I don't see how I could work with him as vice-chairwoman," she told BNS on Friday.
The Liberal Movement's board has recently annulled a decision by the party's Vilnius branch, which is headed by Armonaitė, to run in next March's municipal elections on the ticket of a newly-established public election committee.
The board gave the Vilnius branch until October 31 to reconsider the resolution it adopted last week.
Armonaitė said she could not comply with what she described as the board's "ultimatum" to her branch.
The Liberal Movement's Vilnius branch decided last week to form a public election committee for next March's elections, led by Remigijus Šimašius, the capital's current mayor and a former chairman of the party.
Šimašius resigned as the party's vice-chairman following the board's decision.
Armonaitė said she was not leaving the Liberal Movement, but added that the board might expel her from the party.
Eugenijus Gentvilas, the Lithuanian Liberal Movement's chairman, called on Šimašius and Armonaitė step down as vice-chairpersons after Vilnius' mayor announced his decision to run for re-election as a public election committee's candidate.