A police spokesman said a few hours later that calm had been restored in the city, although several bank branches had been damaged.

General strikes have been common in Greece in recent years as the country has struggled with the privations of recession, high unemployment and the belt-tightening that the country’s foreign creditors have demanded. But Thursday’s general strike was the first under the Syriza-led government of Prime Minister Alexis Tsipras.

Mr. Tsipras came to power in January on a promise of ending years of austerity, but by summer he had agreed to an international bailout program of 86 billion euros, or $92 billion — the country’s third rescue package since 2010 — as the government was running out of money and Greece was on the brink of leaving the euro currency union. To secure the public’s reluctant support for the program, Mr. Tsipras called for new elections and was returned to power by a wide margin in September on a pledge to enforce the new bailout while easing its impact on poorer Greeks.

Though Mr. Tsipras succeeded in purging Syriza of radicals who had resisted a compromise with creditors during his initial term, divisions remain in his party over the issue. An indication of that deep rift was evident this week as Syriza’s labor policy department called for “mass participation” in Thursday’s strike and in the protest rallies planned for Athens and other major cities.