CARACAS, Venezuela—American citizens were among the executives at Citgo Petroleum Corp. that the Venezuelan intelligence agency arrested here on Tuesday, a development likely to exacerbate strains between Washington and Caracas.

Venezuela arrested six top executives of the U.S. subsidiary of state-oil company Petróleos de Venezuela SA, including its acting president, as part of what officials called an anticorruption purge. At least four of those arrested are naturalized U.S. citizens, a Citgo official said on Wednesday....