Ajax completed a £22million move for the Ivory Coast international on Friday, with the 26-year-old signing a four-and-a-half year deal with the Dutch giants.
Speaking ahead of his side's trip to Stockport on Monday for the third round of the FA Cup, Moyes insisted his side were not expecting the offer but sold the forward because there were doubts about whether they would receive another bid of a similar amount.
"We got an offer we weren't expecting," Moyes said. "He has done great for us.
"We wish him well. It is a good move for him. Maybe if we had not taken this offer, we wouldn't have got it again."