Harrison Dunk and Adam Cunnington exchanged two goals in as many minutes as Cambridge and Tamworth drew.
Michael Gash headed wide for the hosts before Richard Tait hit the bar for the visitors in a tight first half.
United took the lead when Dunk fired into the bottom right corner after good work by Gash.
Cunnington's 12th of the season from 25 yards provided an instant response to rescue a point for Tamworth, who are now winless in seven games.
VIEWS FROM THE DRESSING ROOM
Cambridge United boss Richard Money told BBC Radio Cambridgeshire:
"It was a frustrating afternoon for everybody connected to the club. What is not being questioned is the commitment of the players seen this afternoon that are moving forward, in my opinion, in the right direction.
"We have done everything other than win the game but fair play to them. It's disappointing having got in front that we didn't see it through but the players did everything they could to win the game.
"There was some poor decisions made today. I know it's a tough job but I thought the referee had a poor game today because we came out on the wrong side of three or four key decisions."