Tanzania's president, Samia Suluhu Hassan, was declared the winner of the country's elections last week after reportedly taking more than 97% of the vote.
The election result triggered more protests, with some demonstrators tearing down Hassan banners and setting fire to government buildings, according to The Guardian.
Explaining its advisory, the Foreign Office said: "The FCDO advises against all but essential travel to Tanzania. This is due to disruption and unrest following the national election on 29 October.
"There are shortages of food, fuel and cash which have been compounded by the lack of internet services. There is also uncertainty around international transport options."
The FCDO confirmed there's currently a night-time curfew in place between 6pm and 6am, widespread road blockades and closures nationwide.
Many international flights have been cancelled to and from Nyerere International Airport, Dar es Salaam. There are also no ferries running from Dar es Salaam to Zanzibar.
In a statement Audley Travel told TTG: "Following the change in FCDO advice for Tanzania, Audley is arranging for all clients currently in the country to travel home immediately.
"We will also be in touch with all clients with trips booked in the coming weeks to Tanzania to discuss their options.|
Around 75,000 British nationals visit Tanzania each year to have world-class safari experiences, including the Great Migration and wildlife viewing in parks like the Serengeti and Ngorongoro Crater, or climb Mount Kilimanjaro or unwind on the white sand beaches of Zanzibar.