Gandhi used the Hindi word chori, or theft, when he made the accusation while launching the Congress campaign for the assembly polls later this year in Rajasthan.
He claimed that the deal for the French fighter aircraft had led to the loss of jobs for Indian youths, saying the agreement worked out while the Congress was in power would have ensured their manufacture in India.
The Congress president was addressing party workers at the city's Ramlila grounds, where he arrived in a special bus from the airport.
Party workers welcomed him at several points along the 13-km route. After the meeting, Gandhi offered prayers at the Govind Devji temple in the city.
He took a jibe at Bharatiya Janata Party president Amit Shah, saying someone who had been a murder accused is now president of the party.
Shah had been named in the Sohrabuddin fake encounter case, but was discharged by the trial court.
The reference was to the business that foreign manufacturers are required to bring to Indian firms when a defence deal is signed with the government, under the country's offset policy.
Ambani has already rejected Gandhi's allegations and stressed that the government had no role in the French firm Dassault picking up his company as a local partner.
India had signed an inter-governmental agreement with France in 2015 for the procurement of 36 Rafale planes.
Gandhi said the price of the Rafale plane fixed now is about "three times" the amount agreed upon during the previous Congress-led government.
He said the corruption by the prime minister will become clear in the times to come: PM ne Rafale me chori ki hai, jo aane wale time me saaf dikh jayegi.
The Congress chief claimed that only 450 youths get employment in the country every day while China creates jobs for 50,000 people.
Our youths are more honest, capable and stronger than the Chinese but it is a matter of shame that despite having almost an equal population, they are getting fewer job opportunities, he said.
He questioned why Rs 2.3 trillion could be written off as bad loans to 15 or 20 big industrialists, but the government could not help debt-ridden farmers.
When farmers are unable to pay back their loans, they are called defaulters and are jailed. But the bad debts of big industrialists are called non-performing assets, he said.
The Congress leader said the poll promises made by the BJP ahead of the last general election still remained a distant dream.
He said farmers were committing suicide but the government was least bothered about it.
The condition of the women was the worst during the Modi government's term, he said.
In UP, a BJP MLA rapes a woman and entire UP BJP tries to protect him. Incidents occurred in Chhattisgarh also but the prime minister does not speak a word, he said.
We need to protect the 'beti' (daughter) from BJP leaders, he said, mocking the government's Beti Bachao, Beto Padhao campaign.
Gandhi said that demonetisation of high-value currency bank notes and then the Goods and Services Tax (GST), which he called 'Gabbar Singh Tax', had broken the back of the common man and the small businessman.
He said a Congress government will include petrol and diesel under the GST and change it to single-layer tax system.
He said people from the weaker sections are being beaten and killed, minors girls are raped in almost every state in the country but the prime minister does not condemn such incidents.
People depend on courts for justice but Supreme Court judges are now seen begging for justice from people and the press, he said.