The Germany international is in the final year of his contract at the Emirates and, so far, has not renewed his deal with the north London club. The 29-year-old and Alexis Sanchez, who also has less than a year left on his current contract, have not committed their respective futures to the Gunners.
United manager Jose Mourinho has coached Ozil when the pair were at Real Madrid. The attacking midfielder impressed under the Portuguese tactician's guidance and recent reports claim that the player is keen on reuniting with his former boss.
Johnsen heaped praise on the German star after suggesting that a club like United will always be looking to make quality additions to their squad. However, he stressed that he has no information about the 20-time English champions making an approach for Ozil in January.
"I think Mesut Ozil is a fantastic player and United are always looking for quality players to fit in. As a former United player, I know that players with big qualities are always going to come into the club. The big clubs will always look for quality players," Johnsen told IBTimes UK.
"It's always a lot of speculation with players and rumours coming around. You never know anything."
According to the Manchester Evening News, Mourinho's side have not made a move for Ozil, despite the player interested in swapping Arsenal for United in the mid-season transfer window. His current employers, meanwhile, are still hopeful that he will commit his future at the club.
According to reports, Ozil currently earns £154,000-a-week ($203,942 per week) and is demanding a 30% raise at Arsenal, meaning he could potentially earn £202,000-a-week ($267,508 per week). In addition to this, he wants to don the No. 10 shirt, which is assigned to Jack Wilshere.
Ozil is also attracting interest from Italy and Turkey. However, he is reportedly not willing to join clubs from those two nations as he wants leave Arsenal for only three clubs – United, Real and Barcelona.