BRUSSELS—The European Commission urged Ireland on Friday to pursue less restrictive measures than the mandatory hotel quarantine regime introduced last month and sought clarifications as to why some fellow EU member states were subject to the rules. Ireland is the only one of the EU’s 27 countries that forces arrivals from certain countries to pay almost 2,000 euros each to quarantine for up to 14 days in a secure hotel and this week added Belgium, France, Italy, and Luxembourg to its list of designated states that initially also included Austria. The EU executive wrote to the Irish government on Friday in relation to the criteria used to determine the list, a spokesman said. “The Commission has concerns regarding this measure in relation to the general principles of EU law, in particular proportionality and non-discrimination,” the spokesman said. “The Commission believes that the objective pursued by Ireland, which is the protection …