Nevertheless, the EU will not permit anything that damages its single market, he said.
"We respect Britain's red lines scrupulously," Mr Barnier said during a news conference in Berlin.
"In return, they must respect what we are. Single market means single market. There is no single market a la carte."
Following his comments, the pound rose to more than $1.30 for the first time in over three weeks.
Sterling jumped by a cent against the dollar, and was also up by a cent against the euro at just over €1.11.
The currency has been under pressure in recent weeks as traders worry about the consequences of a 'no-deal' Brexit.
Theresa May has said that while a no-deal outcome would not be a "walk in the park", nor would it be "the end of the world".
Mr Barnier's comments came as Brexit Secretary Dominic Raab admitted the UK and EU might miss October's deadline for agreeing a divorce deal.
With negotiations still deadlocked on issues such as the Irish border, Mr Raab called for "renewed energy" to push an agreement over the line.
SKY News.
