The European Commission has requested that the US lift visas for citizens of Bulgaria, Croatia, Cyprus, Poland and Romania.
If within six months the problem is not solved, the EU could introduce visas for US diplomats, the Commission warned, reports EurActiv.
The development comes as a result of the entry into force of a new EU regulation, which requires EU member states to "react in common" on visa matters, especially when third countries have differing treatments for EU citizens from different member states.
The EC requests is said to also apply to Australia and Canada.
The new legislation is an initiative of the European Parliament, which in a 2012 report drew a list of third countries maintaining visa requirements on some EU countries.
According to MEPs, the Lisbon Treaty gives new powers to the Union to request that its member countries are treated as a whole and that the US reciprocates on visa policy.
The five EU countries were reportedly asked by Washington to sign bilateral agreements on data exchange as a precondition for benefitting from the US Visa Waiver Program, writes EurActiv.
One of them is a 2003 provision for the exchange of terrorism screening information (HSPD-6), another being the agreement on Preventing and Combating Serious Crime (PSCS).
But the EC is reportedly not happy that individual countries sign data exchange agreements with the US in the absence of a so-called EU-US Umbrella Agreement on data protection, which ensures EU citizens keep their rights when their data is processed in the US.
Diplomats from the countries lacking reciprocity in their visa affairs told EurActiv that their capitals would notify the Commission of their situation with third countries before the deadline of 9 February.