The 32-year-old played against his former club for the first time during Spurs' 3-2 victory over the Hammers on Monday, and was booed throughout the match.
Parker, who won Hammer of the Year three times during his spell at the club as well as the Football Writers' Association's Player of Year in his final season at West Ham, admits that he was saddened by the events.
"I didn't expect the West Ham fans to boo me and obviously it was a little bit upsetting," said Parker.
"I don't know why [they did it]. I don't know if it's because I went to their local rivals, I'm not sure, but I just would have liked to think that maybe I would have got a better reception after what I did in my time here. I loved [Upton Park], the fans, and I loved the club.
"I had four fantastic years here and it will always be a club with a massive place in my heart. I was looking forward to coming back and I couldn't wait to go out there and play so I was disappointed [to be booed]."
Parker joined Spurs from West Ham for £6m in the summer of 2011.