"To praise a 'zalim' (tyrant) is a crime. I never praised Gujarat Chief Minister Narendra Modi," Vastanvi said at a public rally organised by the minority cell of the Congress party at Tarkeshwar in Mandvi taluka of Surat district.
Darul Uloom Deoband, which has the status of a university, sacked Vastanvi from its vice-chancellorship last year.
"I ask you not to vote for Modi in the upcoming Assembly elections in the state and vote for Congress," Vastanvi told the gathering.
He also asked the community members to unite and urged them to cast their votes in the Assembly elections.
The Congress minority cell sammelan was attended by close to 4,000 minority community members and seven Congress MLAs among other community leaders.
Attacking the BJP for sidelining Muslims during the previous Assembly elections, Bardoli MP Tushar Chaudhary said "Till now, in the previous Assembly elections, BJP has not given ticket to a single Muslim candidate. But now they are fielding Ismail Darbar from Surat because they have felt the need for votes of Muslims."
Assembly elections in Gujarat are scheduled for December 13 and 17 and votes will be counted on December 20.