Collins made her debut as the Rovers Return's new manager Stella Price earlier this month. However, reports have suggested that fans of the ITV1 soap are critical of her attempt at a northern accent for the character.
Marsh wrote in new magazine: "I think viewers are finding it hard to accept because she was such a big character in EastEnders and they still see her as Cindy Beale, which is not fair.
"People should give her a chance. She's only just joined Corrie and it takes time to settle in."
Marsh, who will return to her role as Michelle Connor in September, previously said that she is "dying to see" what storylines await Collins in the Weatherfield serial.
Commenting on an internet campaign to see Loose Women's Denise Welch return to the soap as former landlady Natalie Barnes, Marsh said: "I'd love for her to return - my days at work would certainly be entertaining!"
Read the full story in New magazine - out today.
> 'Coronation Street' team deny Michelle Collins backlash
> Michelle Collins teases 'Coronation Street' revelation