The Belgium coach said "It would be a good thing for both parties" if the striker finds a new club after falling out of favour at Manchester United last season.
Belgium boss Roberto Martínez urged Romelu Lukaku to leave Manchester United ahead of the new Premier League season to get his career back on track.
Lukaku fell out of favour at Old Trafford under Ole Gunnar Solskjaer in the second half of the 2018-19 campaign with Marcus Rashford being preferred.
Reported Inter target Lukaku has acknowledged he would be interested in a move to Italy and hinted last week he may be on his way out of Old Trafford.
Martínez: "It is now important that Romelu finds the right club"
The 26-year-old scored 15 goals in 45 appearances for United in all competitions last term and Martínez stressed the importance of Belgium's leading man finding a new club.
"It is clear that he has to leave Manchester United," Martínez told Belgian outlet Het Laatste Nieuws.
"It would be a good thing for both parties. It is now important that Romelu finds the right club."
Belgium's record scorer Lukaku, reportedly valued at £80million by United, scored three goals for Martínez's men across two Euro 2020 qualifiers earlier this month.