"I urge the EC to take suo moto action against Sidhu and the BJP," he said.
Addressing a public rally in Visavadar Assembly constituency in Junagadh district recently, the former cricketer, campaigning for BJP candidate Kanubhai Bhalala, had termed Keshubhai as an "anti national" leader.
Terming Sidhu's remark as an instance of inciting people in the name of religion, he urged the poll panel to step in.
Daring Modi to point out any instance of anti-national activity against him, he said he should be hanged if there is an iota of truth in the allegation.
"Calling me anti-national tantamount to comparing me with Kasab.
Anti-national citizens are hanged," he said.
"BJP is ready to go at any level to win this election and its comments are highly condemnable," he said.
Keshubhai, who broke away with BJP to form the new outfit, alleged the saffron party itself was the "biggest killer of cows and the highest seller of gauchar (grazing) land".
He said common people will make BJP bite the dust in the upcoming polls.
The Lehua Patel leader is contesting from Visavadar Assembly seat against two-time sitting BJP MLA Kanubhai Bhalala. Congress has not fielded any candidate from the seat.
Visavadar and 86 other assembly seats, spread across Saurashtra, South Gujarat and four talukas in western Ahmedabad, will go to polls in the first phase of voting on December 13, while 97 constituencies spread across Kutch in Western Gujarat and central and northern parts of the state on December 17.
Counting of votes will be held on December 20.