The Trump administration imposed new economic sanctions on Venezuela on Friday, modestly ratcheting up the pressure on the embattled government of President Nicolás Maduro for increasingly repressive policies.

The sanctions restrict trading of Venezuelan bonds sold by the government in the American financial markets to raise money. The effect could increase the likelihood of a Venezuelan default on its debts at the end of the year.

The administration stopped short of prohibiting imports of Venezuelan crude oil to American refineries, which would almost certainly be a crippling step. American refiners have lobbied hard against sanctions against oil imports, arguing that they would raise fuel prices, slash profit margins and potentially cost oil company jobs along the Gulf Coast.

Financial and political analysts said the new sanctions would not represent a lethal blow to Mr. Maduro’s government. But many say its survival over the next year is in serious doubt, partly because of continuing problems raising money to pay interest on its onerous debts while paying for food imports.