The company was recently appointed preferred bidder on the £600m John Radcliffe hospital in Oxford. However, it has been dropped from the final shortlist for a £335m PFI hospital in Birmingham.
A spokesperson for Carillion said: "We wouldn't rule out small bolt-on acquisitions for the construction business, but it's the new businesses where we will be focusing. Construction is about the size we want it."
Carillion's announcement follows a similar decision by Alfred McAlpine. McAlpine aims to spend up to £100m on acquisitions in the services sector. Amey's roads business is seen as a potential target.
The money had been earmarked for a share buyback scheme.
Carillion said in the trading statement that it expected results for the second half of last year to be in line with expectations. The company's share price rose 2.5p after the announcement, closing at 120p last Thursday.