The Dark Knight Rises star has set up a fundraising page for victims of the attack at an Ariana Grande concert on website JustGiving.
The 39-year-old British actor is raising money for the British Red Cross.
He has already raised over £18,812 – more than his original £15,000 target.
The total amount raised so far for victims and their families has now surpassed £2million.
“The killing of innocent families and children unacceptable”
There are currently 150 JustGiving pages dedicated to the cause.
Tom wrote on his JustGiving page: “I am hoping to raise money for The British Red Cross Society because the families and children will need support.
“What happened at the AG [Ariana Grande] concert in Manchester was a tragedy; families and children attacked and murdered; in a place where they should be safe and enjoying a concert – it is an inconceivable atrocity.
“There is no bringing back those who have been lost, pointlessly, in such a cowardly and brutal fashion. I am truly saddened by what I have witnessed and there is no doubt that terrorism is an evil thing.”
He continued: “I hope that between us we can raise some funds as a gesture of goodwill and love to help in some small way towards repairing some if any of the damage done.
“There will be much to do and for many the beginning of a new life without those that they love and also a new life damaged irrevocably by the actions of a crime which has no reason, no heartfelt purpose but was simply a cruel cowardly and barbaric, meaningless act of violence.”
Tom finished off by calling terrorism “abhorrent”, adding: “The killing of innocent families and children unacceptable. And it is with those, the innocent victims and the witnesses of this atrocity that my heartfelt concern and deepest sympathy lies.
“Please help however you can. Thank you.”
The attack, which took place on Monday night, killed 22 people and left 59 others injured.
Tom was labelled a “hero” last month when he chased a thief through London.
Those who want to donate to Tom’s JustGiving page can do so here.