The comments by EU President Donald Tusk, European Commission Jean-Claude Juncker and others weighed into a debate in Britain about holding a second Brexit referendum, AFP reported.
Tusk told the European Parliament that "if the UK government sticks to its decision to leave, Brexit will become a reality with all its negative consequences in March next year, unless there is a change of heart among our British friends."
"We on the continent haven't had a change of heart. Our hearts are still open to you," the European Council chief said in a speech about last month's EU summit.
The former Polish premier was indeed not alone on Tuesday, with Juncker calling on the British government to listen to Tusk about the possibility of reversing its decision.
"Tusk said our door still remains open and I hope that will be heard clearly in London," Juncker told MEPs.
Juncker's deputy Frans Timmermans gave similar encouragement, telling parliament: "If at some point the United Kingdom has second thoughts, or would take another decision, obviously the European Union would leave the door open."
New Austrian Chancellor Sebastian Kurz joined the chorus later, saying in Vienna that he was "happy that this offer has been made. But the decision goes back to the British people."
Britain voted for Brexit by 52 percent to 48 percent in a referendum in June 2016, stunning the world and deeply worrying the EU as it confronted a series of other crises.
Leading Brexit campaigner Nigel Farage surprisingly pushed the issue back onto the agenda last week when he said he was increasingly open to the idea of a new vote.
British Prime Minister Theresa May's spokesman later ruled out a second vote.
"We've been absolutely clear. British people have voted to leave the EU and that is what we will be doing," he said.
European Parliament Brexit coordinator Guy Verhofstadt took a swipe at Farage on Tuesday, saying he had been "disorientated" by his meeting with EU Brexit negotiator Michel Barnier earlier this week.
"I don't know what he (Barnier) put in the coffee or tea of Nigel Farage because he comes out of this meeting and he backs a second referendum," the former Belgian premier said.
Britain and the EU reached a deal in principle on separation issues in December, and are due to start talks next month on a short transition period after Britain's departure in March 2019.
Talks on future relations – including the all-important issue of a possible trade deal, and how closely Britain will stay allied to the EU's single market and customs union – are not due to start until April.