Thackeray said he has not yet decided about supporting Modi in his bid to become prime minister.
Thackeray's remark drew a sharp response from BJP, an ally of his estranged cousin Uddhav Thackeray's Shiv Sena, with its Maharashtra unit chief Devendra Fadnavis saying Modi is competent enough to decide when to quit.
"Modi is performing his duties as chief minister with efficiency. So there is no question of his resigning from his post," he said in Mumbai.
"Modi doesn't speak about Gujarat...He speaks about development, growth, inclusivity, social sector, demographic advantage, jobs...He speaks about India. If Mr Thackeray had listened to Mr Modi's speeches, he would never give such a reaction," Fadnavis said.
