Maddison's exploits for Leicester have seen him reportedly emerge as a transfer target for Ole Gunnar Solskjaer's United.
The 23-year-old England international attacker is contracted to Leicester until 2023.
Asked by a fan if he was staying at Leicester, Maddison said via BT Sport's Twitter account: "Of course I am."
Maddison added: "It was one of the best decisions I've made, coming here. I love it."
Leicester signed Maddison from Norwich City in 2018 for a reported £20 million ($39.3 million) fee.
Maddison has flourished at the Foxes, where he has scored 16 goals across all competitions since arriving.
Before the 2019-2020 season was postponed because of the coronavirus pandemic, Maddison had scored six goals and supplied three assists in the Premier League this term.
Leicester occupied third position in the Premier League through 29 matches when the campaign was suspended last month.