The 28-year-old scored 20 times in Chelsea's 2016-17 Premier League title-winning campaign, but the Spain international is said to have had a strained relationship with Conte in the second half of the season.
Conte is reportedly refusing to change his mind when it comes to Costa, but Pedro is still hopeful that his fellow Spaniard will remain with Chelsea.
"We will see what happens to Diego, but we don't know," Pedro told Cadena Ser. "He is obviously a very important player in attack for us. He has scored the majority of the goals for us this season. He is a player feared by defenders because he is fast. He scores with ease.
"Diego gives you an added strength and more so in this league, because he is strong, he scores and he has good physical condition. If eventually it is confirmed that he will not continue with us, it will be a very big loss for us. It is early days, but I hope as a player and friend that he can stay with us."
Costa, who has been linked with AC Milan in addition to a host of Chinese Super League clubs, has scored 58 times in 120 games for Chelsea, landing two Premier League titles in the process.