Marcelino, 52, took charge of Valencia last summer, and led Los Che to a fourth-place finish in La Liga during the 2017-18 campaign.
Alemany has revealed that Valencia have been "happy" with the Spaniard's work since his arrival at the Mestalla, and has suggested that a contract extension will soon be announced.
"We have a good relationship. Marcelino is happy with us and we are happy with him," Alemany told reporters. "We will have to find the right moment and the best time is when there is no competitions going on.
"In the coming months we will be able to sit down with the advantage that we now know each other well. The fans also know him and the matter must coincide for when there isn't the pressure of matches, so in the not too distant future there will be news."
Marcelino won 26 of his 46 games in charge of Valencia during the 2017-18 season.