"We cannot afford to have a long period of uncertainty. I think that would not be good for either the EU's 27 member states or Britain. But I also understand that Britain needs a certain period of time to analyse the situation," she said.
But while Britain considers its options, the leader of Europe's biggest economy also insisted that no back-room deals would be done before the UK triggers Article 50 to leave the bloc.
"There cannot be any informal talks before Britain gives its notice. That to me, is clear," she said.
British finance minister George Osborne said Monday that his country should only activate Article 50 of the Lisbon Treaty - the clause which allows for the exit of a member state from the EU - when it has a "clear view" of how its future in the bloc would look.
Britain's notification will set the clock ticking on a two-year period of negotiations within which a basic withdrawal agreement should be made.
After that "the treaties shall cease to apply to the state in question" - or in layman's terms, Brexit is a reality.
The talks can in theory be extended if need be -- but only by the unanimous consent of Britain and the other 27 member states.
After the shock result of Thursday's referendum in which British voters chose to leave the EU, London and Brussels have been arguing over the time frame for the start of formal negotiations.
While European leaders have stated clearly they want talks to begin as quickly as possible, London has said it would prefer to wait until the autumn.
Martin Schulz, the president of the EU Parliament, told the Bild am Sonntag Sunday newspaper that he expects the UK to start the talks at an EU summit which is being held in Brussels on Tuesday.
Speaking on Monday in Berlin, Chancellor Angela Merkel's press chief Steffen Seibert said “the German government doesn't want an impasse.”
“That's not in the interest of anyone in Europe. We have a clear process and we should stick to it.”
Seibert emphasized that only the British government can activate Article 50, thereby triggering formal exit talks.
But he said that Berlin does not expect to be kept waiting, adding though, that if the UK needed “a reasonable period of time” Germany will respect that.
Germany will not engage in preliminary informal talks before the UK activates Article 50, Seibert confirmed.
British Prime Minister David Cameron said that he would leave negotiations over the terms of Britain's departure to his successor.
His presumptive successor Boris Johnson, who led the Leave campaign, has been pushing for informal talks, while the Conservative party pick a new leader.
“There will be no informal talks over the exit procedures before Britain has activated the clause. That sequence must be stuck to,” Seibert said.
Everything needs to be done to “strengthen the forces of unity, not those of fragmentation,” Seibert concluded.