Altidore scored just once in 28 Premier League appearances during a loan spell at Hull City in 2009/10, but has been rebuilding his reputation in Holland since joining AZ from Villarreal in 2011.
The United States international has impressed this season and was the subject of a bid from an Eastern European team before the transfer window closed.
The likes of Nick Viergever, Adam Maher and Markus Henriksen have also shone this term, with Stewart claiming Chelsea and Tottenham are among the clubs to have been in attendance at AZ matches.
"I can confirm that there was a bid for Jozy from a wealthy club from Eastern Europe," Stewart told the club's official website in response to questions from fans.
"The bid was received at a very late moment, therefore we couldn't sign an adequate replacement. For us, it wasn't interesting.
"Also, Jozy was keen to stay at AZ. After years of travelling, he has really found a home. He doesn't want to just leave the club.
"However, I won't say whether interest will increase during the winter break or at the end of the season. Jozy is developing fantastically, is a real target man for the team and translates that into goals.
"Something like that isn't missed abroad. Also this season scouts from big clubs like Barcelona, Bayern Munich, Chelsea and Tottenham Hotspur have visited AZ games."