Filmmaker Karan Johar got a rude wake-up call Friday when Maharashtra Navnirman Sena (MNS) activists protested the use of 'Bombay' instead of Mumbai in his latest movie "Wake Up Sid" as soon as it was released.

Directed by Ayan Mukerji, the film, starring Ranbir Kapoor and Konkona Sen Sharma, is the latest offering from Dharma Productions Pvt Ltd.

Even as angry activists vociferously protested the movie and tried to disrupt its screening in at least two south Mumbai cinemas, a harried Karan rushed to meet MNS chief Raj Thackeray at his Shivaji Park residence.

"He has tendered an unconditional apology for this faux pas which the party has taken serious note of, " MNS vice-president Vageesh Saraswat told.

Emerging from the meeting a short while ago, an aggressive Raj said that such things (using 'Bombay' instead of Mumbai) would not be tolerated and Karan has realised his mistake.

"He has sought time from us to rectify the error. We shall wait for three-four days before the next step, " Raj told mediapersons outside his residence.

To a query, he said that not only the directors, but all persons connected with filmmaking and other fields must ensure that Mumbai is used in place of 'Bombay'.

"When the names of other cities like Delhi and Chennai are not changed, why should Mumbai be change to 'Bombay'?" he thundered.

Saraswat said that Karan explained to Raj the complications about deleting and replacing 'Bombay' with Mumbai since over 700 prints have been sent worldwide for a simultaneous release.

"However, Karan Johar assured the MNS chief that he would be able to insert an apology at the start of the movie. We shall wait and watch. If the apology is not shown as promised, we shall plan our further steps in the matter, " Saraswat warned.

"Wake Up Sid" has been released in 42 cinema halls in Mumbai alone and another 150 in the rest of Maharashtra, according to an industry analyst.