HOUSTON — The Trump administration on Friday granted Chevron, the last major American oil company operating in Venezuela, three more months to produce oil and gas in the South American country, which it hit earlier with sweeping sanctions.

The announcement, from the Treasury Department, was made with no fanfare and was not viewed as a fundamental change in the administration’s policy toward Venezuela. President Trump has made clear that he thinks President Nicolás Maduro ought to hand power over to an interim government to pave the way for an election.

The administration banned American companies and individuals from dealing with Venezuela’s state-owned oil company, Petróleos de Venezuela, or Pdvsa, on Jan. 28, but it granted Chevron and four United States oil service companies a six-month waiver. That exemption has now been extended to Oct. 25.

The sanctions essentially shut Venezuelan oil out of the United States, that country’s most important market by far. It also prohibited the sale to Venezuela of lighter grades of American crude, which the South American country blends with its heavy oil to move the fuel through pipelines. Venezuela’s oil production has collapsed nearly 50 percent over the last year, to 760,000 barrels a day in June, according to S&P Global Platts.