The ban also applies to Germany, Netherlands and Russia, which will severely affect Morocco’s tourism industry just as it was recovering.
It comes as UK Covid rates in the last seven days reached 40,000 per day.
Royal Air Maroc said it would allow unlimited changes of ticket date and destination, free of charge until 15 December 2021 to the same or another destination.
Clients can also opt for vouchers valid for 12 months and refundable in cash on the expiry date. However, cash refunds are only possible at the same point of sale that issued the original ticket.
A UK Foreign Office spokesperson said travellers impacted by the ban "should contact their airline or tour operator for advice on alternative routes via third countries where flights are operating as normal."
Following the announcement, easyJet cancelled all outbound flights from the UK, Germany and the Netherlands until 30 November.
A spokesperson for the airline said: "We have two flights operating from the UK from Manchester and Gatwick to Marrakech which we will operate as ferry flights to return customers due to travel back today.
"We are still awaiting clarity from the Moroccan authorities as to whether we are permitted to operate repatriation flights beyond midnight today.
"Pending guidance from the Moroccan government, we intend to fly inbound in the coming days to offer passengers repatriation flight options.
"We are contacting all customers whose flights are cancelled with their options which include a free of charge transfer, receiving a voucher or a refund."
Tui has cancelled flights to Marrakech and Agadir until 31 October.
A spokesperson said: "We are contacting customers in departure date order to discuss their options, which include amending to another destination or a full refund.
"We are working through the details of this announcement with the Moroccan authorities and will be updating customers currently on holiday in the next 24 hours.
"We would like to thank our customers for their patience and understanding during this time."
