The European Commission has said it will wait for the Dutch government to suggest a way forward.
Options include leaving the Ukraine agreement in force provisionally, or drafting exemption clauses for the Netherlands.
Manfred Weber, leader of the centre-right European People’s Party (EPP), the biggest bloc in the European Parliament, and an ally of German Chancellor Angela Merkel, said the referendum result was a “big defeat” for the Dutch government and should be taken seriously.
Speaking to Deutschlandfunk radio he said: “We need to make Europe more democratic and transparent.”
He added politicians need to engage more with citizens, explain things to them and show that they take people’s concerns seriously.
He said that applied particularly to Britain ahead of the June referendum on the country’s membership of the EU.