The AAP leader remarks came soon after its all three party candidates from Chandni Chowk lost in the civic polls.
She will, however, continue to support and "provide strength" to Delhi Chief Minister Arvind Kejriwal and the AAP's fight against corruption till it reaches its logical conclusion, she added.
"We all know that in this kind of environment, fight against justice and corruption is not easy. Even then this fight will continue till there is a change," Ms Lamba, who had quit the Congress to join AAP in 2013, said in another tweet.
Last year, the AAP had removed Alka Lamba as its spokesperson, reportedly for straying from the party line on a minister accused of corruption.
Soon after the counting of votes began and the BJP showed all the possible signs of retaining all three municipal corporations, the AAP leaders including Deputy Chief Minister Manish Sisodia assembled at Mr Kejriwal's residence to ponder over the party's poor show.
(With inputs from PTI)