The Bosnian army was sent to erect tents as shelter for hundreds of migrants at the burnt-out Lipa camp after protests.
Top EU leaders have criticised Bosnia for its response to the growing crisis at a burned-out refugee camp near the country's border with Croatia.
Trying to resolve a humanitarian disaster, the Bosnian military set up tents on Friday for hundreds of migrants who have been stuck at a fire-ravaged camp that has no facilities to fend off freezing winter weather.
Bosnia has faced international criticism for leaving some 1,000 migrants without shelter after a fire engulfed the squalid Lipa refugee camp in the northwest of the country over a week ago.
The armed forces said on Friday that about 150 soldiers had arrived to put up tents for the migrants, which will be run by the International Organization for Migration (IOM).
Josep Borrell, the bloc's foreign affairs representative, said on Friday evening that the situation was "unacceptable" and would be damaging to Bosnia's reputation.
In a tweet, he said: "Unacceptable situation in #LipaCamp area. Lives need to be protected.
"#BiH authorities agreed to provide for winter proof solution - decisions need action. Fully fledged #EU funded facilities available. Disregarding political state responsibilities detrimental for BiH reputation".
Ylva Johansson, the EU Commissioner for Home Affairs, voiced her agreement with Borrell, adding that an equipped centre available in the nearby town of Bihac should be used instead.
Quote tweeting Borrell, she said: "Fully agree. Emergency tents at #LipaCamp are necessary immediate response for coming 2-3 days.
"But the Bira centre will allow these 900+ people to get through the winter. You should not rely on first-aid only when a ready made ‘ambulance’ is available".
Local residents in Bihac, supported by municipal officials, have so far resisted the reopening of the Bira centre.
Earlier on Friday, the migrants held a protest to highlight the horrendous conditions they are facing in Bosnia. Aid groups said hundreds of migrants rejected food and held up banners calling for international help.
The authorities announced earlier this week that they would move the migrants from Lipa to a former army compound in central Bosnia but plan was rejected after local residents organised protests.
The migrants spent 24 hours in a convoy of buses, waiting to move, but ended up back in the burned-out Lipa camp instead. For the past two nights, they have lit fires to warm up at the muddy camp site.
Bosnia has struggled with the influx of thousands of people fleeing war and poverty in their countries in the Middle East, Africa, and Asia. Migrants mostly flock to Bosnia's northwestern corner, which borders European Union member Croatia, from where they hope to move toward wealthier European countries. But many have reported violent pushbacks by Croatian border forces as well as hostility from Bosnian residents.