The winger made his England debut last season before injury struck.
"That is a good shout," says Lampard.
"I spoke to Gareth (Southgate) and all I can do is say what I see from a Chelsea end and it is Gareth's choice. Callum has probably not played enough games and the international games will do him good.
"It is England Under-21s and he should be proud of that anyway."