He made the remarks after meeting with an African Union's delegation currently visiting Sudan to discuss preparations for the next peace talks in Abuja, Nigeria.
The Sudanese government has fulfilled all its commitments to the joint committee for the ceasefire, Khalifa said, adding that the humanitarian and security situations in Darfur has improved.
On AU exerted efforts to hold the upcoming round of Abuja talks in May, Khalifa said "that needs arrangements with all parties concerned in the issue."
Sudan's arid and impoverished western region of Darfur has been in the grip of civil war for more than two years, after black African residents rebelled against what they see as persecution from Khartoum's Arab-led government.
Thousands of people are estimated to have been killed and more than a million driven from their homes during the violence.
The AU has brokered a shaky ceasefire and sent a small force of military observers, but three previous rounds of talks in the Nigerian capital Abuja has failed to find a political solution so far.