Di Matteo has enquired about taking the young Frenchman on a season-long loan as he looks to bolster his attacking options for the Premier League.
Ngog enjoyed his best season for Liverpool last term, featuring in 37 matches in all competitions and scoring eight goals, but he never managed to nail down a regular spot under Rafa Benitez.
However, the striker's agent said on Tuesday that he will not be leaving Anfield on loan this summer as new boss Roy Hodgson "likes him as a player".
Di Matteo, though, is not giving up hope just yet.
"He is a player we are interested in," he told Albion's official website.
"But most clubs wait until the end of July and the beginning of August before deciding on which players they might loan out."