Ajmal was suspended with immediate effect by the International Cricket Council (ICC) on Tuesday, after tests showed "all his deliveries exceeded the 15 degrees" by which the arm is allowed to bend when bowling.
The news represents a major blow to Pakistan, who are now set to take on Australia in all three formats without their premier bowler.
However, the 36-year-old can apply to have his action re-assessed and Pakistan plan to appeal the ICC's verdict.
Citing a "not usual" elbow as the reason for his ban, Ajmal has pledged to return for the World Cup, which takes place in Australia and New Zealand from February.
"My elbow is not usual so that's why it seems that I bend it more than the normal 15 degrees allowed. We will go into appeal soon," Ajmal told reporters in Faisalabad.
"I will be in action in the World Cup next year, that's my resolve.
"They [the ICC] are yet to consider my medical reports. Once they do it I am sure there shouldn't be any problem."
Pakistan Cricket Board (PCB) chairman Shaharyar Khan also confirmed an appeal was set to be launched and expressed his surprise at all of Ajmal's deliveries being deemed illegal.
"Our experts understood that it is the doosra [a delivery that spins in the opposite direction to a standard off-break] that may be suspected but that proved wrong because his entire action was called illegal," said Khan in quotes reported by Cricinfo.
"That's a concern for us but we are going to appeal because we want to understand if the ICC has covered all the angles or not.
"We have two weeks to lodge an appeal. We have to face this with courage and go through it without panicking."
Ajmal, who boasts 446 international wickets and is the number-one bowler in the ICC's ODI player rankings, previously had his action investigated in 2009 only to subsequently be cleared.