The priority of the EU's remaining 27 member states would be to protect their social and economic interests, Sigmar Gabriel told German parliament, a day after British Prime Minister Theresa May launched the two-year negotiation process to quit the bloc.
Tusk speaking in Valletta, Malta on Friday morning.
But that concession to British Prime Minister Theresa May two days after she triggered a two-year countdown to withdrawal was accompanied by elements in the draft that May might find less palatable.
"The European Council (EU leaders) will monitor progress closely and determine when sufficient progress has been achieved to allow negotiations to proceed to the next phase" on a future relationship, the draft guidelines say.
The proposal says that the status of European Union citizens living in the United Kingdom must be settled; a legal vacuum for companies once European Union laws no longer apply to the United Kingdom must be prevented; the bloc must ensure that the United Kingdom honors its financial commitments and liabilities; and a hard border between Northern Ireland and the Republic of Ireland must be avoided.
"Once and only once we have achieved sufficient progress on the withdrawal can we discuss the framework for our future relationship", European Council president Donald Tusk said at a press conference in Malta on Friday morning.
Also, Britain could pay as much as $63 million to the European Union to cover staff pensions and other obligations, according to the EU.
Government sources familiar with discussions with Mr Tusk's office say they expect the guidelines will be "quite short and terse", and will concentrate on broad principles and objectives rather than detailed outcomes.
"The talks which are about to start will be hard, complex and sometimes even confrontational", Tusk said proposing draft guidelines for Brexit talks.
Johnson, speaking in Brussels upon arrival for a North Atlantic Treaty Organisation meeting Friday, said he has had good feedback from partners since Wednesday's British announcement, despite worries on both sides of the Channel about Brexit. In her trigger letter to Tusk, May called for trade talks to move ahead "alongside" the divorce.
But it may also suggest that the question of the UK's "divorce bill" must be settled in advance of the vital trade talks.
He said: "A big mistake that we could make from both sides is to start with launching threats to each other".
European Union states and authorities in Brussels are much cooler toward that idea, seeing a future trade deal with Britain as a strong bargaining chip.
It is understood the guidelines contain explicit references to the Northern Irish peace process and the border between Northern Ireland and the Republic.
This means that businesses in the United Kingdom will officially lose access to the EU's single market on March 29, 2019 - unless they agree on a transition deal.
The EU citizens living in the United Kingdom, among them Hungarians, contribute greatly to the country's achievements, Lindsay said.