A senior police officer said the Chinese-made low intensity explosive went off in front of a new shop in the area around 5 am.
The blast did not cause any casualty or damages and could be related with monetary demands, the officer said.
The shop is owned by one Aribam Bimol (50) who also runs a jewellery outlet in the state capital.
Meanwhile, Manipur police commandos swung into action and arrested one suspect identified as 45-year-old Y Somorendro from his residence at Napet Palli area in Imphal East district, the officer said, adding his direct involvement in the incident is not yet confirmed.