The 23-year-old has attracted attention after his 10 goals so far this season helped Stuart McCall's side rise up to third in the SPL.
His current Fir Park deal expires at the end of the season and while he will be able to sign a pre-contract with another club from January, Murphy is adamant his only focus at the moment is getting results on the pitch.
He said: "I've not spoken to anyone. I just expect the speculation now, to be honest.
"That's about three or four transfer windows I have been experiencing this kind of speculation.
"I just try to get on with it and when the club comes to me and says they have accepted a bid from someone, that is the only time I will go and speak to them."
Murphy accepts that an imminent departure from Fir Park is likely, but is adamant he has not given his long-term future much thought.
He added: "I don't really have a preference [which club he joins]. If a team thinks I am good enough to play for them and they put in a bid, then I will speak to them.
"I have been here for 11 years and until someone tells me otherwise, I will remain here.
"I have not spoken to [Motherwell chief executive] Leeann Dempster or the gaffer about Sheffield United, but I'm sure if something happens they will tell me about it.
"I have not spoken about a contract extension either and I don't know when I will. I am just trying to play football."
With Motherwell having been beaten only once in their last eight SPL matches, Murphy is enjoying life at Fir Park and believes both himself and the team can continue to improve.
He said: "It's good for the team to be on a good run of form to get up the league table. We want to push up as high as we can.
"I'm playing well right now I think and there is more to come. The team is playing well just now, too."