The commission said the death toll could be underestimated due to challenges in identifying victims.
The mission highlighted loss of lives, internet shutdown, and voter apathy, among other factors that made the exercise below democratic standards.
Mrs Hassan’s swearing-in ceremony was held on Monday at the State House in Dodoma, the capital, under tight security.
Netblocks, a platform tracking cybersecurity and digital governance, confirmed internet restoration in Tanzania on Monday.
Several days of disruptive electoral protests have caused food, fuel, and cash shortages in Tanzania.
The party claimed the election was rigged and vowed not to recognise Samia Suluhu Hassan as the East African country’s president.
The UN urged potesters to demonstrate peacefully.
Mrs Hassan has secured another five-year term.
Mr Dada was Uganda’s military dictator between 1971 and 1979.
The opposition party said at least 700 people have been killed in the protest.
