The reduction -- beginning on January 1 -- comes following the recent decisions by OPEC and non-OPEC oil-producing countries to cap output.
"We have started advising our customers of the expected reductions in oil deliveries to ensure the state's compliance with OPEC's allocations," said a statements from Saad Sherida Al-Kaabi, president and chief executive of state-owned Qatar Petroleum.
"This decision comes in line with the state of Qatar's commitment to the recently agreed production levels by the members of OPEC during its ministerial meeting held on 30 November, 2016."
On November 30, Qatar was among the OPEC countries which agreed to reduce output by 1.2 million barrels per day (bpd).
This was followed earlier this month by non-OPEC oil producing countries agreeing a cut of 558,000 bpd.