The Scot used a news conference to fire back at City's former player Patrick Vieira for saying earlier in the week that United had shown their weakness in bringing Paul Scholes out of retirement.
"If it's desperation bringing the best midfielder in Britain for the last 20 years back then I think we can accept that," said Ferguson.
"(City manager) Roberto (Mancini) had a wee dig a couple of weeks back. We're all going to play our hand that way. There will be plenty of ammunition for that," he added.
"If you talk about desperation, they played a player the other night who refused to go on the pitch and the manager said he'd never play again and he takes a five-month holiday in Argentina.
"What is that? Could that come under the description of desperation? There will be plenty of ammunition don't worry," smiled Ferguson.
Former United striker Tevez is back in favour at City after being absent since September when he refused to come off the bench in a Champions League match in Munich.
Mancini had said the Argentine would never play for City again but sent Tevez on for the final 20 minutes against Chelsea on Wednesday and was rewarded by the player setting up the winning goal in the 85th minute.
City are now one point behind champions United with the two rivals meeting for a potentially decisive clash at the Etihad stadium on April 30.
Tevez scored 24 goals last season but had hardly been missed while City were riding high in the league until patchy away form whittled away their lead and allowed United to steal back in front.
Vieira, now City's football development executive after a long career with Arsenal, had said Scholes' return "shows a little bit of weakness in United, because they had to bring a player back who was 37.
"With all the respect I have for Scholes, him coming back shows that they don't have talent in there to replace him," added the Frenchman.
Vieira had also said that the departure of young United players such as Ravel Morrison and possibly Paul Pogba was worrying for the champions who would previously have had no problem retaining talent.
Ferguson also rejected that accusation and hoped Pogba would be staying.
"We want him to stay because we think he's going to be a fantastic Manchester United player. We hope that's the case," said the Scot.