TEHRAN, Iran — In her appearance before the Gulf Cooperation Council (GCC) summit on Dec. 7, UK Prime Minister Theresa May called for deeper military cooperation with members of the Arab bloc and said the United Kingdom and its allies must work together to counter “Iran’s aggressive regional actions.” In this vein, she told leaders of Saudi Arabia, Kuwait, the United Arab Emirates, Qatar, Bahrain and Oman, “As part of the renewed relationship that I want to forge with you, the United Kingdom will make a more permanent and more enduring commitment to the long-term security of the Gulf.”

Her posturing immediately raised eyebrows in Tehran, leading Iran to issue a warning against London about the consequences of a possible greater future role in the region.

The day after May’s comments at the GCC summit, the chairman of the parliament’s National Security and Foreign Policy Commission, Alaeddin Boroujerdi, told Iranian state TV, “If Britain seeks to persist with such a policy vis-a-vis the Islamic Republic of Iran, the parliament will once again move to downgrade relations.”

The furor comes as bilateral ties have just fully resumed after years of tension. In late November 2011, the UK severed relations following an attack on its diplomatic facilities in Tehran. After an almost two-year freeze, the two countries agreed in October 2013 to appoint nonresident charges d’affaires as a first step toward re-establishing diplomatic ties. Iran and the United Kingdom upgraded their mutual diplomatic representation back to the ambassador level in September, in another sign of warming relations between the two countries.