"Today, I have signed into law ... the Comprehensive Peace in Sudan Act of 2004, ... intended to help resolve conflict, reduce human suffering and encourage freedom and democracy," Bush said in a statement on Thursday.
The Sudan act, passed on 7 December by the US Senate and in November by the House of Representatives, aims to respond to the conflict in Darfur, providing support for the deployment of additional African Union forces to the region.
The bill also sanctions the government of Sudan for its failure to intervene to stop the atrocities in Darfur, imposing an asset freeze on senior Sudanese officials and calling for a travel ban for those officials.
The legislation also authorises $100 million as an incentive for the warring parties to reach a final and comprehensive peace agreement.
US Department of State spokesman Richard Boucher on Monday said the United States "is gravely concerned by the intensified violence that has been taking place in Darfur in recent days".
He added that "both sides need to pull back and respect the ceasefire".
Boucher made his remarks as African Union mediators met delegates from the Sudanese government and two main rebel groups in a bid to revive stalled talks on the fighting that has left an estimated 70,000 people dead and 1.5 million displaced.
Harmful to US
Reacting to the US bill, Sudan's chief negotiator in the Abuja peace talks with Darfur rebels, Majdhub al-Khalifa, told Aljazeera: "The US legislation would not harm the Sudanese government, and would not benefit the Darfur rebels, but would harm the interests of US companies."
Al-Khalifa said the "so-called Comprehensive Peace in Sudan Act passed by the US Congress has not deterred Sudan from continuing its economic development, with the help of other countries such as China and a number of Southeast Asian countries, and even some European countries".
Up to 1.5 million people have
been displaced by the conflict
"The US law has in fact turned into sanctions against US companies, by depriving them from opportunities to participate in development projects in Sudan," he said.
Al-Khalifa added: "We are committed to peace based on our own will, while the US role is receding in Sudan due to its unwise stand, which would only increase hostility towards the US."
The negotiator said the Sudanese government was about to sign the long awaited peace accord in Naivasha, adding that the joint statement issued by the African Union, the Sudanese government and rebel movements in Abuja last week marked a turning point from the standpoint of ending ceasefire violations and promoting peace.
Al-Khalifa said these developments indicated that negotiations would resume next month with the aim of putting an end to the crisis.
Al-Khalifa dismissed possibilities of a US move to freeze the assets of Sudanese officials and government-run businesses in the US, saying it will have no effect since no Sudanese official has assets or funds in US banks.