Rice will be good enough for England – Pellegrini
The defender, who can also play in midfield, has made three appearances in friendlies for the Republic of Ireland, for whom he has featured at various youth levels.
But Rice was not included in Ireland's squad for their Nations League opener against Wales and manager Martin O'Neill confirmed the 19-year-old is considering overtures from England.
Rice has only played 45 minutes in the Premier League this term, but Pellegrini is confident he has the talent to make the grade for England.
"He has a big problem, but I think that his heart must decide if he feels more Irish or more English," said Pellegrini. "He is 19 years old and his future will allow him to play for England or Ireland.
"Maybe for him it can be more easy to play for Ireland, but if you trust in yourself and you feel that you are an English player… It is a personal decision, it is very difficult to give advice, but I am always speaking with him because he is young and he has a lot of future.
"With the way he is managing his career, at 19 years old, he is a player that is completing his development as a player in a physical way.
"When you are 19 you need to be strong – he is a strong player, he is a good technical player. I think he has a big future.
"With England he will have big competition, but I think he is able to take that challenge, without giving him a decision. He must take the decision himself."
that win was needed tonight! We need to build on this go again Saturday! Big thank you to all the traveling fans again #COYI
— Declan Rice (@_DeclanRice) August 28, 2018
Rice has yet to comment on his international future, but he posted on social media after West Ham came from behind to beat Wimbledon in the EFL Cup on Tuesday – a game he started in midfield.
"That win was needed tonight!" Rice wrote on Twitter. "We need to build on this and go again Saturday! Big thank you to all the travelling fans again."