The Spanish champions have already brought in forwards Mario Mandzukic and Antoine Griezmann this summer to compensate for the departures of Diego Costa, David Villa and Adrian Lopez, but Simeone revealed he is still looking for an extra forward.
Although an instant hit when he first arrived at Old Trafford, Hernandez has struggled to get into United's first team in recent years, starting just 15 Premier League games in the last two seasons.
However, Simeone still believes the Mexico international would be an asset to his side.
"He's great in one-on-one situations and he's someone who could be useful to any team," the Atletico coach told a press conference in Mexico, ahead of his team's pre-season friendly with Club America.
"We are speaking to the sporting directors about the type of player we want and then it's up to them to bring the player in
With Javier Hernandez and lots of other great players, anything is possible
We can't close any door until the transfer window shuts."
Simeone also praised new arrival Griezmann, who officially joined Atletico from Real Sociedad on Tuesday for an estimated 30million euros (£24m), saying that the Frenchman was a more versatile player than Diego Costa, his side's top scorer last term who signed for Chelsea earlier this summer.
"Costa gave us speed, power and the chance to counter quickly, but Griezmann gives us more options," said the Argentine.
"He has enormous power and we'll have to see where he can perform best for us
At Real Sociedad and with France he's played on the wing so we'll see how he adapts to the team."
And Simeone insisted he was not interested in taking the vacant Argentina job after Alejandro Sabella announced he would not be staying in the job, but admitted he would like to take charge of his country in the future.
"I have been committed to Atletico for a long time, they are the club that opened the doors of Europe to me and made me grow as a coach," he said.
"I'm focused on Atletico and not thinking about Argentina
Also, no-one has spoken with me (about the Argentina job) so we are talking about a hypothetical situation
I would love to become the Argentina coach at some point, but I'm focused on Atletico."
Source : PA
Source: PA