Villa meet Arsenal tonight in London sitting just three points behind the Premier League leaders.
Asked about giving his squad a boost over the winter market, Emery said: "We are alert and if we can sign someone to help us and really improve, we will do it. We can sign players, only we can't spend a lot. But we can do something and of course maybe change (move on) players as well.
"We want to be ambitious to achieve our objective. Our objective is European football. When I came here three years and two months ago, it was to have a new experience in the Premier League, and to try to build this team to fight for trophies and play in Europe consistently."
Meanwhile, on their title chances, Emery encouraged fans to "dream".
He added: "Dreams are free. Everyone has to dream. I have my dreams and I am getting them here. My huge dream here, or as a coach, is to win the Champions League. This has been my dream all my life.
"Last year we played in the quarter-finals of the Champions League and I was coach of Villarreal when we went to the semi-finals in 2022.
"But then we are realistic. Right now, the only dream I have is tomorrow's match. Of course we can analyse how we want to build the club and where we want to get to but now it is all about tomorrow."