The off-spinner was cited for a suspect topspin action following a one-day series in Sri Lanka in October but recently returned to bowling.
PCB officials wrote to the world governing body asking them to clarify the 23-year-old Shoaib's position and there was even a suggestion that he should be allowed to "bowl without inhibition" in future.
But the ICC re-iterated their longstanding position that no bowler can ever be given a lifetime clearance because of the risk of re-offending.
In a letter to the PCB, David Richardson the ICC's general-manager, cricket, wrote they had noted a considerable improvement in Malik's bowling action in Pakistan's recent tour of India, as confirmed by the Pakistan board's own biomechanical report that it recently commissioned from South Africa.
"We are pleased to note that Shoaib appears to have made improvements to his action and that he was recorded as bowling within the levels of tolerance of elbow extension as laid down in the ICC regulations by the biomechanical research commissioned by the PCB," said Richardson.
"This seems to confirm what the match officials reported to us following his bowling during the recent ODI series in India, where they said that he was bowling with a much smoother action."
However, the former South Africa wicket-keeper added: "There can be no guarantee that he will not be reported again should his action deteriorate. As regards the request that Shoaib be given ICC clearance to bowl without inhibition in the future, I would like to clarify the position as follows:
"The effect of the report from the biomechanical expert cannot be to clear the bowler to bowl without limitation in the future. This would obviously not make sense as a bowler could then, once cleared, simply revert to old bad habits."
"As with all bowlers, whenever Shoaib bowls in a match in the future, his action will be under the scrutiny of the match officials. According to ICC regulations they will use the naked eye to determine whether his action complies with the Laws."
"You will recall that the degree of permitted elbow extension is 15 degrees and that this level of tolerance was set at the point at which such elbow extension will begin to become noticeable to the naked eye. Accordingly, any degree of extension which is visible to the naked eye must and will be reported."
"Shoaib has proven himself a fantastic young cricketer and we are hopeful that he will continue to work on his action to ensure that the improvements that have taken place become permanent."
Earlier this month Malik was banned for one Test and fined 75 percent of his next two international match fees by the PCB for throwing a domestic game.
Leading his hometown Sialkot team, he admitted throwing a Twenty20 tournament match against the Karachi Zebras as a protest after his team were penalized for a slow over rate in another match.
Malik will miss Pakistan's first Test against the West Indies in Barbados starting on May 26. He has so far taken eight wickets in eight Tests but 84 wickets at 99 one-day internationals at an average of just over 34 apiece.
In February the ICC endorsed a change in the laws governing fair deliveries by allowing all to straighten their bowling arm up to 15 degrees, established as the point at which any straightening, resulting in an illegal 'throw' becomes visible to the naked eye.