He said the people should not be deceived by fake rumours about travelling abroad and asked them to avoid coming to the airport, Afghan media reported.
The Duke and Duchess of Sussex posted a joint statement on their Archewell Foundation website encouraging followers to unite and support organizations "doing critical work" to help those in need.
He described the images coming out of Afghanistan as "gut-wrenching" but said: "I've learned the hard way that there was never a good time to withdraw US forces.
It appears that desperate Afghans were clinging on to either the undercarriage of the C-17 or the landing gear of the transport plane when they got flung out due to the huge G-force exerted during take-off.
Given the deteriorating security situation, we support, are working to secure, and call on all parties to respect and facilitate, the safe and orderly departure of foreign nationals and Afghans who wish to leave the country