Without taking Modi's name, Gandhi told an election rally in Jharkhand that some opposition leaders were selling dreams, as if "they will change everything in one day with a magic wand".
"Will the country chose a prime minister a person who will be a big liar?" she said at Ramgarh in Hazaribagh district.
"In a democracy, just anyone should not be allowed to grab power." But she did not refer to Modi by name in her speech.
Gandhi urged Maoists to shun violence and join the mainstream of the society.
And in an appeal to coal workers, she also said that it was former prime minister Indira Gandhi who nationalized the coal mines in order to improve the lot of the labourers.
She detailed the achievements of the Congress-led UPA government in the last 10 years.