Addressing an election rally here, Modi also said that the secularism plank of the Congress had failed to attract voters ahead of this Lok Sabha election.
"The game of secularism is over. So Congress leaders are taking the route of communalism to get votes," Modi said in an apparent reference to Gandhi's meeting with Syed Ahmed Bukhari, the Shahi Imam of Delhi's Jama Masjid.
Gandhi had reportedly asked Bukhari to ensure that "secular" votes didn't split in the election beginning April 7.
Modi expressed surprise that the Election Commission had not taken notice of the incident despite news channels running the Sonia-Imam meet story since Wednesday.
"Why has the Election Commission not issued any suo moto notice?" he asked.
The Gujarat chief minister said the BJP stood for unity and development whereas the Congress believed in divide and rule.
"For us secularism means every community is our own. For the Congress, secularism is just an election plank...
"The Congress refutes my talk on development by raking in secularism. They know they are going to lose," Modi said.
The mantra of the Congress was to divide the country, Modi said, adding Gandhi was now openly seeking support from Muslim clerics.
"Whenever I talk about development, they say talk about secularism. Whenever I talk about farmers, they say talk about secularism... They had not realized that one day a tea seller would come this far..."
He said secularism was a slogan for the Congress while it was a mantra of development for the BJP.
"Secularism is a slogan for the Congress to hide its shortcomings. For the BJP it is a national commitment.
"For the Congress secularism is a tool to divide the country. For the BJP, it is to unite the country."
The Bharatiya Janata Party has fielded former Indian Army chief, General V.K. Singh, in Ghaziabad.
The general told the rally that he took to politics at the urging of activist Anna Hazare.
Ramesh Chand Tomar, the Congress candidate from Noida who joined the BJP, announced his full support for Gen Singh.