The Daily Star says United took up the option of triggering the 12-month extension on Herrera’s original deal that will keep him at Old Trafford until the end of next season.
But Herrera has seen Marcos Rojo handed a three-year-deal last month, despite the fact the unsettled Argentine could still leave United.
Herrera’s representatives have started talks with United executive vice chairman Ed Woodward about a similar deal, with Mourinho keen to tie him down for the long term.
Herrera, who joined United in a £30m deal from Athletic Bilbao in 2014, said: “I am going to fulfil the year that I have left, but I don’t know if I will renew.
“We have started talking, although nothing has been decided yet.
“But I think the manager is very happy with me, the fans are very happy with me, so that makes me really proud.”