Sabella also said Argentina’s status among the favourites would be countered by the fact they will be playing in the backyard of the most successful team in the competition with five titles.
Messi has had a troubled few months and been the butt of criticism for Barcelona’s drop in form, including their Champions League quarter-final elimination and slipping four points off the pace in La Liga.
“Messi is fine but we must try to be the best possible team to help him,” Sabella said.
“We have to get the team to be more compact, occupy the spaces,” he said in an interview with news agencies at the Argentine FA’s training complex on the outskirts of the capital.
“Messi has matured as a person, he has interior peace, but we have to create a climate that will allow him to be happy, I think we have to let him be calm,” the 59-year-old said.
“He’s already played at the World Cup, he didn’t score goals but he created many chances, only there were goalkeepers who had brilliant afternoons,” Sabella added, referring to the 2010 tournament in South Africa.
Messi has played at two World Cups having made his debut at in Germany as a teenager in 2006 and scoring one goal. At both tournaments, Argentina went out to Germany in the quarter-finals.
“The objective we need to aim for is to be in the last four where Argentina have not been for some time,” Sabella said.
Twice champions Argentina last played in the semi-finals in 1990 in Italy.
“We must go step by step, getting there is not easy and in the last 16 or quarter-finals you can get more complicated opponents, you can have a bad day and those teams can send you home,” he said.
“Generally, Argentina have gone to the World Cup with an aura (of favourites), there’s the passion, the desire and forecast that they could be world champions, I think it’s always been like that,” Sabella said.
“This time a bit more so because Messi’s has been in his splendour in the national team and because we’re playing in our neighbour’s backyard and can almost feel like we’re at home.
“But what happens with that backyard is that it belongs to the biggest winners of World Cups, the five-times champions and we’re going to be more like visitors than ever,” added Sabella, whose greatest moment as a coach was when his Estudiantes team won the South American Libertadores Cup final in Brazil in 2009.
Sabella had a scare when one of his leading players, Fernando Gago, was injured playing for Boca Juniors last week but he said he was confident the midfielder would be fit for the tournament starting on June 12.
“He’s coming here for his medical check-ups, he looks okay to me, he won’t have problems (getting to Brazil). It’s probable he’ll be short of football because of a period out of action and due to a lack of full movement of his knee,” Sabella said.
Sabella considers Gago to be Messi’s ideal ball provider on the right side of midfield. His understudies are Lazio’s Lucas Biglia and Ever Banega of Newell’s Old Boys.
Argentina meet Bosnia in Rio de Janeiro in their opening Group F match on June 15. They also face Iran and Nigeria.
(Additional reporting by Luis Ampuero; Editing by Osmond)