The ban, which takes effect immediately, was imposed after independent analysis of Botha's deliveries during South Africa's third Test defeat by Australia in January.
Botha finished the match, his Test debut, with figures of 1-26 and 1-77.
ICC General Manager David Richardson, said that the ban would apply until Botha could show he had remedied his action to comply with ICC rules that a bowler's arm should not be flexed at the elbow by more than 15 degrees.
"The independent report has identified excessive levels of straightening in both his off-break and doosra deliveries," Richardson said in a statement.
"It is now up to Johan to remedy the concerns that have been identified ahead of a reassessment which will be necessary if he is to return to international cricket.
"Johan is a young player and there is nothing to stop him making a successful return to international cricket with a remodelled action."
Botha has an unusually high action and is one of the few bowlers to have mastered the "doosra," a delivery perfected by Sri Lanka's Muttiah Muralitharan, which spins from leg-side to off-side for a right-handed batsman.
The initial report on Botha's suspect action was made on January 6 by on-field umpires Billy Bowden and Aleem Dar, TV Umpire Bob Parry and ICC Match Referee Chris Broad.
The independent analysis was conducted at the University of Western Australia (UWA) and Botha could opt to challenge their assessment through the ICC's Bowling Review Group.
Under ICC rules, Botha would face an automatic one-year ban if he were to return to international cricket and be found to be using an illegal action once more.
Botha is the fifth player to have undergone an independent review of his action since a new process for the review of suspected illegal actions was introduced in March 2005.
The other players are Harbhajan Singh, Shabbir Ahmed, Shoaib Malik and Jermaine Lawson.