Shiv Sena activists Tuesday attacked several places that will screen Shah Rukh Khan's "My Name Is Khan", barely an hour after Mumbai Police assured full security at the 63 cinemas and multiplexes that will showcase the movie.

Sena mobs attacked and damaged the booking windows of the Mehul Theatre in Mulund and staged noisy protests outside Shreyas Theatre in Ghatkopar, both in the suburbs, officials said.

Groups of Sena activists were also seen protesting and shouting slogans in Kanjurmarg, Bandra, Khar and other parts of the city even as police promised tough measures to prevent any untoward incident during the release of the film directed by Karan Johan and also starring Kajol.

While 12 Sena activists were nabbed from Mulund, 24 were detained in Ghatkopar and Kanjurmarg in connection with the protests.

Earlier in the afternoon, director Karan Johar had called on Police Commissioner D. Shivanandhan and returned satisfied by the police security promised for the movie.

Joint Police Commissioner (Law and Order) Himanshu Roy said anybody attempting to disrupt the film in any manner would be dealt with "very firmly".

"We shall also frisk and search suspicious persons coming to view the movie to prevent any untoward incidents inside the cinema auditorium, " Roy told a packed news conference.

The Sena violence came a few days after the party had unofficially dissociated itself from banning the movie release in the city.

However, on Tuesday, senior party leader and former Lok Sabha speaker Manohar Joshi reiterated in Nagpur that Shah Rukh must apologise for his remarks advocating the cause of Pakistani cricketers participating in the Indian Premier League. His much awaited film is slated for a global release this Friday, including 63 cinemas and multiplexes in Mumbai and another 250 across the state.