The task force, which has been led by a senior American officer, is based at a Jordanian military training center built into an old rock quarry North of Amman, The New York Times reported.
American officials familiar with the operation said the mission also includes drawing up plans to try to insulate Jordan, an important American ally in the region, from the unrest in Syria.
The US outpost near Amman has been playing a broader role in recent weeks. It is less than 35 miles from the Syrian border and is the closest American military presence to the conflict.
Officials from the Pentagon and Central Command, which oversees American military operations in the Middle East, declined to comment on the task force or its mission. A spokesman for the Jordanian Embassy in Washington would also not comment on Tuesday.
The American mission in Jordan quietly began this summer. In May, the United States organized a major training exercise, which was dubbed Eager Lion. About 12,000 troops from 19 countries, including Special Forces troops, participated in the exercise.
After it ended, the small American contingent stayed on and the task force was established at a Jordanian training center North of Amman. It includes communications specialists, logistics experts, planners, trainers and headquarters staff members, American officials claimed.
"We have been working closely with our Jordanian partners on a variety of issues related to Syria for some time now," said George Little, the Pentagon press secretary.
In a similar revelation on Tuesday, media outlets disclosed that British secret services have sent tens of troops to Syria to help rebel and terrorist groups in their fight against the Damascus government.
A former HSBC bank clerk is among as many as 50 British men fighting in Syria alongside rebels and terrorist groups.
The men, predominantly of South Asian and North African backgrounds, are understood to have joined the Syrian terrorist groups since the battle began last year, according to security sources.
The bank clerk, from Birmingham, is understood to have travelled to Syria earlier this year, about 12 months after leaving his job at HSBC, the Sunday Times reported.
In addition to the former bank worker, a man in his early thirties of Pakistani origin, the Britons are understood to include an NHS doctor.
In June, Daily Start reported that the British defense chiefs had drawn up secret plans to start covert military operations in Syria.
The report said SAS troops and MI6 agents were in Syria ready to help armed rebels and terrorist groups if civil war breaks out as - expected this weekend.
They also had hi-tech satellite computers and radios that could instantly send back photos and details of Assad's forces as the situation develops.
Whitehall sources said it was vital they could see what was happening on the ground for themselves.
"And if civil war breaks out the crack troops are on hand to help with fighting, said the insider," the report said.
British Foreign secretary William Hague has refused to rule out using military action against the Syrian government.
A senior Whitehall source said the British forces were due to create "safe havens for the rebels in Syria", admitting that "safe havens (operations) would be an invasion of Syria".
"The SAS will throw an armed screen round these areas that can be set up within hours.
"There are guys in the communications unit who are signalers that can go right up front and get involved in close-quarter fighting."
The rebel Syrian Free Army has dismissed the UN-backed truce and has continued attacks on not just military centers, but civilians despite the ceasefire required by the peace plan.