The Wolves forward has 15 goals in the Premier League this season as his side sit five points off a Champions League place, with United one place above them.
Juventus have been mooted as possible destination for Jimenez, but Martino said he thinks the former Benfica man would be a better fit for Ole Gunnar Solskjaer's side as they do not have anyone like him.
"Looking at it from the outside today I cannot see a specialist No. 9 like Raul at United," Martino said on ESPN show Futbol Picante. "There are many forwards like [Marcus] Rashford, [Anthony] Martial and the boy who now plays as right winger: [Mason] Greenwood but since Romelu Lukaku left I can't see a pure No. 9 like Raul.
"At Juventus he will have more of a fight because [Cristiano] Ronaldo shares the inside of the pitch with whoever plays alongside him, with [Paulo] Dybala or with [Gonzalo] Higuain and maybe he has a tougher fight there."
Martino was Barcelona manager in the 2013-14 season but left after 12 months, with his only trophy success having come in the Spanish Super Cup, but he said Jimenez would be better prepared at a big club, having already played for some of Europe's top teams earlier in his career.
"We who see it from the outside, you [the journalist] and even me, always have the idea that a player has to aim for more and how good it would be for him to go to play for Manchester United," Martino said. "For me, that at one point in my life I was in a very big club [Barcelona], and having lived a difficult year there, I say that you have to be convinced of the step you want to take and you have to analyse it from many places.
"And he has elements to analyse it because, although he has not been at Manchester United, he was at Atletico Madrid and he was at Benfica. And he has elements to put in the balance to decide what he wants from his life.
"Maybe he wants a bigger challenge because he feels that he is in good shape and has to take advantage of it, maybe he wants to stay in this place, maybe the options you read about are not real and do not exist.
"I think the best thing is for Raul to make the decision based on the analysis he makes and with the consensus of his family because, when it comes to enjoying, not only the player suffers and enjoy, but also the family do it."
While Martino said he would love to have players available for selection who play for some of the biggest clubs in the world, he did not want to get involved in Jimenez's personal decisions.
"I am not one of those who believe that the manager should decide for the footballer when we are outside, having nothing to do with him," he added. "I agree that we would all love to have players at Barcelona, Real Madrid, Manchester, Tottenham, Juventus.
"I appreciate it, but these decisions are very personal and I do not know if the managers should get so deeply into this because we don't know the context in which the player has to decide. This is a decision for his close camp."