The Northern Irishman claimed Cao failed to declare an illegal push shot during a 10-6 first-round defeat.
Allen later apologised for his comments and will now be obliged to undergo media training.
World Snooker said the ban would only come into effect if Allen made any new breach of rules in the next six months.
His latest punishment follows a previous case in March where he was fined £1,000 and warned as to his future conduct for comments he made about China and the Chinese people on Twitter.
He was also fined £250 in January for swearing in a press conference at the UK Championship in December last year.
A World Professional Billiards and Snooker Association statement said: “The WPBSA disciplinary committee consider that this behaviour is unacceptable and offensive to China and the Chinese players. Such behaviour will not be tolerated by the WPBSA.”
Allen was also ordered to pay £1,000 towards the cost of the hearing.