Manangagwa said the attack had been “calculated to achieve a bloodbath” and destabilise the ongoing electoral programme.
“My hunch without evidence is that the people who aggrieved by the new dispensation… are the G40 so that is the logical conclusion,” Mnangagwa told the BBC.
“I think this is a political action by some aggrieved persons by the current democratic dispensation in the country.” he added.
The president further said Grace Mugabe was “politically immature and was easily used by a tool who wanted to get at me”.
Many of those who were close to the former first lady have fled Zimbabwe.
Opposition leaders in Zimbabwe fear the bombing may serve as a pretext for a wide-ranging crackdown by the government or the military but Manangwa dismissed such concern.
“There is no need for a security crackdown; this is a criminal activity”, he said.
“But of course we must make sure the population is protected and only when we have got them are we going to be able to assess the extent to which the network is spread.”