The clarification of Washington's position came as France launched fresh air strikes on the fifth day of its military intervention in the West African nation.
Paris has poured hundreds of soldiers into Mali and carried out air raids since Friday in the northern half of the country, which was seized last year by an Islamist alliance combining al Qaeda's north African wing AQIM with Mali's home-grown MUJWA and Ansar Dine rebel groups.
Western and regional states fear the insurgents will use Mali's north, a vast and inhospitable area of desert and rugged mountains the size of Texas, as a base for international attacks.
"There is no consideration of putting any American boots on the ground at this time," Mr Panetta told a news conference yesterday after meeting his Portuguese counterpart on the first leg of a trip to Europe.
Mr Panetta said on Monday the US was considering providing France with logistical, reconnaissance and airlift support.
He added yesterday no final decision had been made on what kind of help to offer France or when. He said: "We have commended the French for this effort to try to go into Mali to stop the AQIM, these terrorists and members of al Qaeda, from being able to develop a base of operations in Mali."
A senior US defence official said Washington was already sharing intelligence with France and that would continue.