The European Commission, the EU executive, voiced objections to the deal last month, another source had told Reuters, increasing pressure on Cemex to offer concessions to allay its concerns.
Cemex has convinced the European Commission that the deal will not reduce competition in Spain, continued the Reuters source, who reportedly declined to be named because the decision is not yet public.
Commission spokeswoman Emer Traynor, Cemex and Holcim declined to comment on the decision, which will be made public by September 12 2014, when approached by Reuters.
The EU competition watchdog's preliminary review showed the takeover would substantially curb competition in the grey cement market in certain parts of Spain.
The Spanish deal is part of an exchange of assets between Cemex and Holcim announced in August last year, with the companies keen on cost savings to offset tough conditions in the construction sector.
Holcim gained unconditional EU clearance last month to buy Cemex's German businesses. It is now in informal talks with the Commission on its plan to merge with French peer Lafarge to create the world's biggest cement maker.
