Lukashenko government lashes out, saying no ‘self-respecting’ state would agree to demands posed by the West.

The U.S. and European Union imposed sanctions against Belarus officials on Friday, part of a coordinated effort by Western allies to censure the authoritarian regime over accusations of political repression and rigging elections.

The EU reached an early morning deal to advance a sanctions package against more than three dozen Belarusian individuals deemed responsible for suppressing protests and for election fraud. Hours later, the U.S. Treasury Department blacklisted eight senior figures in longtime President Alexander Lukashenko’s government or associated with his rule. Among those blacklisted were Interior Minister Yuriy Khadzymuratavich Kareau and top election commission officials.

The EU’s action against Belarus, together with a joint statement reprimanding Turkey for drilling in waters claimed by Cyprus and Greece, was meant as a broader message of mounting concern that Europe’s eastern periphery, a region that once held hopes for a spread of democracy, is increasingly turning back to its authoritarian past.

Divisions within the EU stymied an attempt to sanction Turkey during a summit this week, but officials said the bloc could approve punitive actions in the future.

The EU was able to move forward with its Belarus sanctions package, originally promised in August, after Greece and Cyprus secured the statement calling for Turkey to halt its drilling.

While the U.S. sanctioned Mr. Lukashenko in 2006, the EU declined for now to include the Belarussian leader himself in their action. Officials said the president, who previously was the subject of EU sanctions that were lifted in 2016, still could be targeted again later.

The EU sanctions came into effect Friday afternoon. Mr Lukashenko’s interior minister was also one of the highest-profile names on the EU sanctions list.

The Belarus foreign ministry condemned the sanctions and said the government also enacted its own sanctions list, which won’t be made public. It said it may also reconsider its participation in joint programs with the EU and could cut diplomatic ties if further EU sanctions are levied.

“The sanctions were introduced as a punitive measure…for the fact that Belarus did not comply with a set of ultimatum requirements that no self-respecting sovereign state would satisfy,” the foreign ministry said in a statement. The statement didn’t address the specific allegations of election-rigging and violent political repression.

The U.S. and EU sanctions follow the imposition of sanctions on Mr. Lukashenko and seven senior figures in his government by the U.K. and Canada on Tuesday, a sign of widening discontent in the West over ongoing repression of peaceful protests against his purported victory in a disputed election.

Western officials have accused Mr. Lukashenko and his allies of multiple human rights violations in detaining and allegedly torturing protesters following the Aug. 9 vote, which Mr. Lukashenko’s opponents and Western governments say was rigged in his favor to extend his more than a quarter-century in power.

The EU has called for a rerun of the presidential elections with international supervision. It has warned it could add additional sanctions if Mr. Lukashenko refuses to enter dialogue with the opposition.

The U.S. sanctions targeted officials the Treasury Department said run government offices responsible for the political repression, human rights abuses and election fixing. Besides the top two Interior Ministry officials, the Treasury also blacklisted the two leaders of Interior’s Internal Troops, Yuriy Henadzievich Nazaranka and Khazalbek Bakhtsibekavich Atabekau.

“The Belarusian people’s democratic aspirations to choose their own leaders and peacefully exercise their rights have been met with violence and oppression from Belarusian officials,” said Treasury Secretary Steven Mnuchin.

The Trump administration declined for now to revoke a special license giving the nine largest state-owned companies in Belarus access to the U.S. financial system, as urged by the U.S. Commission on Security and Cooperation in Europe, a government body that advises administrations on sanctions.

While the EU’s Belarus sanctions had broad support, the bloc has been deeply split over how to respond to Turkey’s increasingly frequent flexing of military muscle in the region, including its unilateral moves to explore and drill for energy resources in the eastern Mediterranean. Turkey says it has the right to seek energy resources in the region.

With respect to Turkey, the EU leaders settled on diplomacy for now, issuing the joint statement but threatening sanctions if Ankara didn’t show willingness to improve ties.

Western diplomats said tensions between Ankara and Athens this summer rose to levels not seen since the 1970s, when Turkey and Greece came close to a direct military conflict over Cyprus. Greece and Turkey are North Atlantic Treaty Organization members.

However, Turkey has for now suspended its energy activities in waters claimed by Greece but not by Cyprus. Separately, Turkey and Greece reached an agreement Thursday, mediated by NATO, to take measures to avoid an air or naval clash in the eastern Mediterranean, including a hotline between the two countries.

European diplomats have also grown alarmed by Turkish President Recep Tayyip Erdogan’s decision to send troops into Libya and Syria, its unconditional support for Azerbaijan in renewed fighting with Armenia and its acquisition of advanced weaponry from Russia.

On Thursday, French President Emmanuel Macron said France had clear evidence that jihadist fighters were leaving Syria to go to fight in Nagorno-Karabakh via Turkey. Mr. Macron had earlier criticized Ankara for what he called its bellicose comments against Armenia over its conflict with Azerbaijan.

—Ann Simmons in Moscow contributed to this article.