Mr Durkan said: “I unequivocally condemn those behind this brutal attack in our community, especially during the Christmas period and season of goodwill.
“My thoughts are with the man who was injured in this disgraceful attack and his family at this difficult time.
“There remains a group of individuals who defy the will of this community for peace.
“Those who have brought violence onto our streets need to understand, and they need to be made to understand, that they represent no one and have attacked all of us.
“I would urge anyone with information to get in touch with the PSNI or with Crimestoppers.
“We need to take back our communities from these people. That can only be done if people volunteer information.”
Investigating officers say that an altercation between two men took place in the Aileach Road area of the city, shortly before 2.30 pm on Boxing Day.
Detective Sergeant Brian Reid said: “We would like to hear from anyone who was in the area close to the Ringfort Road roundabout on the Aileach Road around this time and saw what happened.
“It was reported that a man who was carrying a yellow plastic bag was shot in the leg by a second man.
“The assailant made off on foot, carrying what we believe was a handgun.
“The victim was able to walk to a nearby church where he contacted police.
“We believe this was a paramilitary-style shooting and although the man’s injuries are not life-threatening, this was a brutal attack and yet another example of how criminal groups seek to control communities through fear and violence.
“Anyone with information about this crime or who may be able to help identify the perpetrator should contact detectives at Strand Road on the non-emergency number 101, quoting reference 619 of26/12/17.
“Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.”