Undersecretary-General for Peacekeeping Operations Herve Ladsous said troops with the U.N. Disengagement Observer Force were scaling back operations after 21 members of the force were captured but later released, in Syria.
"We have had to reduce somewhat the footprint of UNDOF in the Golan Heights in the area of operation," he said in a statement.
UNDOF monitors the cease-fire that ended war between Israel and Syria in the 1970s.
Ladsous said the force may get reinforcements from Arabic-speaking officers in the coming weeks.
The Security Council in December extended the UNDOF mandate to June 30. The council said it considered the escalating conflict in Syria when voting to support the mandate.
The United Nations said its decision was based specifically on the presence of Syrian military forces and unauthorized military equipment in the area.
Israeli forces in November fired on Syrian positions in response to fighting in and around the occupied Golan Heights.