The spokesman said he could not imagine any conditions under which parliament would not be given one more chance to vote on approving a Brexit deal.
He added that Theresa May has been very clear that Britain will be leaving the EU on 29 March.
In January, the UK House of Commons rejected the Brexit plan that was presented by Prime Minister Theresa May after months of negotiations with the European Union.
Theresa May has rejected calls for a second referendum, pointing out that the United Kingdom should not delay its withdrawal from the European Union.
UK citizens voted to withdraw from the European Union on 23 June 2016 via a nationwide referendum.