The All-Star guard told ESPN that the fan called him a "b----."
"It was just unnecessary," Thompson told ESPN.
The incident happened midway through the fourth quarter Friday night at the BMO Harris Bradley Center, when Thompson fell to the hardwood near the fan after being fouled.
While on the floor, the fan leaned over and began spewing expletives. Thompson was shocked and began calling attention to the fan's behavior.
West told ESPN the fan shouted to Thompson: "F--- you, b----. You m-----f-----."
"He was wild, man," West said.
Once ushers approached the fan, he claimed he didn't say anything but eventually left his seat without further incident.
Thompson finished with 12 points and five rebounds in 35 minutes of play. He was 0-for-2 on 3-pointers, ending a league-leading streak of 95 straight games with a field goal from beyond the arc.