A man was reportedly struck with a spanner as a mass brawl broke out at a city football training session on Monday night.
Two people were injured during the disturbance in Whitfield, including a player and a coach.
The incident happened around 8pm when a team from Dundee Thistle FC training at the pitches at the new North East campus became the main target for the gang.
Ian Smith, from the club, said: “I witnessed for myself the absolute disgrace that is happening at the new school at Whitfield.
“We were training with the team and a group of about 30 youths aged 14-16 started congregating.
“A few of the gang started throwing stones at the boys.”
He said the police appeared and moved the gang on but they re-appeared later.
“They weren’t interested in playing football, just fighting, and a player and a coach were assaulted, the coach with a spanner to the head,” Mr Smith said.
“This was nothing short of a disgrace.”
>> Keep up to date with the latest news with The Tele newsletter
A spokesman for Police Scotland said: “We are investigating two alleged assaults on Lothian Crescent, at around 8pm yesterday.
“A group of youths on bikes caused a disturbance at a football pitch where a team was holding a training session.
“A 48-year-old man and 16-year-old boy were assaulted by two members of this group.
“Officers are following a positive line of inquiry and inquiries are ongoing.”
Local parent Stacey Anderson, 30, said there were nightly problems with gangs of youths at Whitfield.
She said: “Up to 100 of them congregate regularly at the playpark next to the school.
“They cause a lot of trouble and vandalism.
“It gets really scary at times.”