Hart did play in last week's Champions League tie against Viktoria Plzen, but Pantilimon has been the man in possession since the start of November and impressed against Swansea on Sunday.
Pellegrini said: "Joe Hart continues to be the number one of England. He is a very good goalkeeper.
"But Pantilimon has played seven games - four in the Premier League in which he has conceded just one goal - so that is also important for the team.
"They are two important goalkeepers. I trust in both of them. At the moment I am playing Pantilimon, but you saw the other day when Joe Hart played he did very well."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball