The 34-year-old joined the League One outfit at the beginning of the season and has emerged as one of Swindon's key players.
"It is up to the manager, but I am very happy here and I am pleased with how things have been going, although it is the club's decision," Ward told the Swindon Advertiser.
"All I have been doing is playing and enjoying it, and hopefully that can continue and I can carry on contributing to where the club wants to go.
"It would be very interesting and something I would be keen on, but it is still a little way away and hopefully we can continue to do well."
It is not yet clear whether Millwall would be prepared to sell the experienced defender.