Dar es Salaam police chief Lazaro Mambosasa confirmed the abduction saying security forces were on high alert hunting for the kidnappers.
The businessman and former politician was reportedly pursued by numerous armed individuals as he made his way into a Dar Es Salaam hotel.
Reports from the scene suggest two white men and an unknown number of accomplices in two cars waylaid the prominent businessman as he walked into the exclusive Colosseum Hotel and Fitness Club, where he is a member.
"There were two white people involved, we are yet to establish the motives behind abduction", Mr Mambosasa said, adding that investigations are underway.
Dewji, the owner and president of the multi-billion dollar revenue Mohammed Enterprises Tanzania Ltd (METL Group), was seized as he arrived for a morning workout at a luxury hotel in the country's commercial capital.
Dewji was born in Tanzania and studied at Georgetown University in Washington DC.
Dewji was elected to parliament on the CCM ticket but did not seek re-election to his seat in the 2015 election.
He also said three people have been arrested in connection with the incident.
He is also the main shareholder in Tanzania's Simba FC football club.
They then pulled him into their vehicle and sped off while shooting in the air.
Meanwhile, NAIJ.com reported that Nigerian business mogul, Aliko Dangote, remains Africa's richest person with $12.2 billion net worth, according to the latest 2018 global list released.
Dar es Salaam regional commissioner Paul Makonda cautioned the public against speculation.