The airstrikes carried out on Thursday "would lead to consequences", Pajhwok News quoted Zabihullah Mujahid, a Taliban spokesman, as saying in a statement.
"American occupation forces carried out airstrikes in Kandahar and Helmand, causing casualties to civilians and some mujahideen," the Taliban said the statement.
While denouncing the strikes as barbaric, the militant group slammed them as a clear violation of the agreement between the US and the Taliban.
"(President) Ashraf Ghani recently made an announcement that he has planned major operations in the next six months," the statement added.
During the period, the outfit said, responsibility for all military developments would fall on the leaders of the Ghani administration, the report said.
Mujahid said the fighters would defend areas under their control.
The insurgents would not remain in a defensive posture if the government forces insisted on war, he warned.
Under the withdrawal deal between the Taliban and the administration of former US President Donald, all foreign troops were to leave Afghanistan by May 2021.
But in April, President Joe Biden said all US troops would be brought home by September 11, a decision that drew strong criticism from the Taliban.