Ahmad said on Twitter: "If the blast near BJP's office in Bangalore is a terror attack, it will certainly help the BJP politically on the eve of election."
The state assembly elections are due May 5.
Congress general secretary Janardhan Dwivedi said that any terror incident is a matter of concern. "...it is a national and international problem... it is a challenge for the country... it should not be seen as political gain," Dwivedi told reporters after the blast in Bangalore, in which 16 people were injured.
Ahmad's party colleagues distanced themselves from his tweet, saying the party had nothing to do with it and it was his personal view.
"I have not seen his tweet. What he said is his personal view and the party has nothing to do with it," added Minister of State for Home R.P.N. Singh.
However, an undeterred Ahmad tweeted again in the evening: "Karnataka HM (home minister) R. Ashok says blast near our office was aimed to kill BJP leaders due to elections. This will also generate some sympathy."
Ahmad's remarks were criticised by the BJP as unwarranted and uncalled for.
"Such remarks are uncalled for and should not have come from a senior Congress leader. The party (Congress) has already accepted defeat in Karnataka," added BJP spokesperson Meenakshi Lekhi.
"There should be no politics on such incidents," BJP leader Shahnawaz Hussain added.
Condemning Ahmad's remarks, BJP president Rajnath Singh said: "Terrorism should not be seen as a political loss or gain."
Stating that the incident was "unfortunate and condemnable", he said party leaders were taking stock of the situation.
"I talked to Karnataka Chief Minister Jagadish Shettar. We are taking stock of the situation," Rajnath Singh said.
Sixteen people were injured, two of them seriously, in the explosion in crowded residential locality of Malleshwaram in north Bangalore. Many vehicles were gutted but there was no damage to the BJP office in the explosion that was initially believed to be a cylinder blast.