"It is therefore deeply regrettable that a United Kingdom air strike on 26 March 2018, targeting Daesh fighters in eastern Syria, resulted in an unintentional civilian fatality", Defense Secretary Gavin Williamson said in a written statement to Parliament.
It was not immediately clear whether the USA -led coalition or Iraqi forces were behind the strike.
In a statement, task force officials said that during a news conference, officials confirmed the SDF will return to offensive operations against ISIS in the middle Euphrates River valley.
U.S-backed Kurdish forces in Syria say they are resuming their campaign against Islamic State militants who still control areas near the border with Iraq.
"The regime is now collecting information on our operation to make sure we, along with the coalition, fail in our mission against IS", he told VOA, adding that the Syria government "conspires to attack our forces each time we prepare to liberate the Syrian soil from terrorism".
The announcement by the SDF comes less than a week after USA defense secretary Jim Mattis said he expects to see "re-energized" efforts against ISIS in eastern Syria.
On Twitter, the diplomat noted that the operation will involve a United States-led coalition and "local partners", including the Syrian democratic forces.
"The fighting will be hard, but we and our partners will prevail". She said the SDF will "liberate those areas and secure the Syrian-Iraqi border and end the IS presence in eastern Syria once and for all".
US officials have repeatedly said their battle against IS in eastern Syria's Deir el-Zour has been complicated by the close proximity of the Syrian regime, backed by Russian Federation and Iranian-linked Shiite militias.
Deir Ezzor Military Council head Ahmed Abu Khawla told AFP there was a "shared operations room with Iraqi forces".
French special operations forces arrived in Syria last month to help boost US-led efforts against ISIS, US Defense Secretary Jim Mattis said last week.
Turkish forces captured Afrin in March.
The SDF alliance, spearheaded by the Kurdish YPG forces, has seized vast tracts of territory from IS in north and east Syria.
"It had a very big and wide impact on the liberation, which was stalled for months".
The United States intends to defend against ISIS border of Turkey, Israel, Jordan, Iraq and Lebanon.
"IS retains a significant presence near the Iraqi borders from which it seeks to retain a safe haven to plan attacks around the world and expand its territory in Syria and Iraq", Abdallah added.
But ISIS has since lost much of that territory to various offensives in both countries.