The European Securities and Markets Authority (ESMA) said in a statement that the four countries "will shortly announce new bans on short-selling or on short positions."
This was "to restrict the benefits that can be achieved from spreading false rumours or to achieve a regulatory level playing field, given the close inter-linkage between some EU markets."
In France the chairman of the Financial Markets Authority (AMF), Jean-Pierre Jouyet, told AFP the body had decided to ban short-selling of 11 shares for two weeks.
The ESMA did not detail the measures to be taken in the other three countries.
The decisions were taken after securities regulators in Paris said the French stock market had plunged since Wednesday because of unfounded rumours.