Manchester City have criticised Carlos Tevez for a "significant error of judgment" after he waved a banner reading "RIP Fergie" during the club's title-winning parade. The newly crowned Premier League champions also apologised to Sir Alex Ferguson and Manchester United for the striker's conduct.

Tevez was handed the placard, which had the offending words written on the image of a gravestone, by someone in the crowd watching the club's celebration on the streets of Manchester.

The move prompted hundreds of Twitter users to voice disquiet at a gesture that may be viewed in bad taste due to Ferguson being 70 years old. Tevez later issued an apologetic statement but that did not save him from criticism from his club.

A City spokeswoman said: "The creation of the tasteless material is in itself reprehensible and in accepting and brandishing it, Carlos has made a significant error of judgment.

"The club wishes to express its sincerest apologies to Sir Alex Ferguson and Manchester United Football Club for any offence or distress caused."

The meaning behind the banner could well be a reference to Ferguson's famous response when asked three years ago if United would ever be underdogs against City. "Not in my lifetime," he said.

Tevez was smiling as he lifted the banner above his head on the top of City's open-top bus parade but later said: "I got carried away in the excitement of the moment and I certainly didn't mean any disrespect to Sir Alex Ferguson, who I admire as a man and a manager."

Tevez played for two years under Ferguson at Old Trafford before leaving for City in 2009. United's manager said at the time that the striker, who had been on loan, was not worth the asking price to sign permanently. "Quite simply he is not worth £25m," he said.

This is not the first time that Tevez has upset his employers at City. He spent more than three months on unauthorised leave in Argentina after falling out with the manager, Roberto Mancini, for refusing to warm up at Bayern Munich.

Tevez's conduct soured City's celebration of their first top-flight title since 1968. The club have, though, inevitably started thinking about next season and are determined to take a tough line over their strategy in the transfer market this summer, refusing to pay over the odds to strengthen their squad or sell any player for less than their valuation.

With the demands of Uefa's financial fair play regulations City know they may have to sell before operating towards the higher end of the market, with up to 11 of Mancini's squad potentially available and Eden Hazard, the Lille attacking midfielder, among their prime targets.

The club believe that Milan's failure to prise Tevez away in January for less than the £25m asking price, despite the striker's dispute with Mancini, provided a watershed decision that underlined their refusal to let players leave on the cheap.

Ferguson claimed on Monday night that City "are going to spend fortunes, pay stupid money, pay silly salaries" but that is disputed by Khaldoon al-Mubarak. City's chairman said on Monday there would be "no major changes", as Mancini is generally content with his squad. Mubarak also stated the club's long-term vision is to focus on the development of homegrown talent.

Mubarak told the club's website: "Let's start from this point - this team we have is a championship team, it's won the Premier League so we're not starting from the same point of any other pre-season over the last four years.

"We had to improve in a very dramatic manner. Today we have a very strong nucleus, a nucleus that has won the FA Cup [last year] and Premier League and that has improved as a team together.

"It's important to harness that nucleus and improve in a tactical way because we always want to improve and get better at all levels. You are not going to see any major changes. I think there's going to be improvement but in a very manageable way."

Regarding the development of players from City's academy, Khaldoon added: "It's crucial when you look at FFP, when you look at what the academy does for the community and how we manage the evolution of his cub over the next ten years, it's fundamental to our growth strategy and success to have a successful programme that produces young talent into the first team."

Khaldon praised Roberto Mancini, the manager for his willingness to "evolve". He said: "Roberto is a winner. We have got very close over the years, I know how he works. We have all learned a lot. This has been a learning experience. His ability to continue to devolve. This is where I credit him the most. He's not fixated. He accepts you have to evolve. And you look at this season the way we have managed some very difficult situations over the season and managed to accomplish your objective to win the league it's a credit to Roberto's managerial skill and his team.

"He has a very strong character, he wants to win more than anyone I've ever seen. He's so driven to winning, it gives you confidence and an incredible amount of energy and I think this is a manager who will do a lot of great things for this club."

He is also content with the work of Brian Marwood, the chief football operations officer. "We have the right scouting, the right management of that, I have the highest regard for Brian Marwood for what he has accomplished in that area," he said.

Mario Balotelli missed the City parade due to being called up by Italy along with Yaya Touré who was in Monaco getting treatment on the hamstring he injured in Sunday's 3-2 win over Queens Park Rangers that sealed the championship.