"I'm happy that today, with a trilateral meeting we had in Brussels between the European Commission, the Russian government and Ukrainian government, there was broad support for this," European Commission President Jose Manuel Barroso said in Kiev on Friday.
"Let's see if this can now be the basis for a compromise."
Moscow has threatened to block Ukrainian goods to Russia if Kiev lowers trade barriers with Europe.
The EU said it would allow Ukraine to maintain its current tariffs until early 2016, but it would still have to undertake major economic and political reform required by the agreement.
Earlier in the day, Ukrainian president Petro Poroshenko proudly announced that legislators would ratify the landmark deal with Europe on Tuesday, pivoting his country firmly toward the West over half a year after its pro-Russian leader was ousted from power following moths of protests.
Speaking to Ukrainian and European politicians and business leaders in Kiev on Friday, Poroshenko said he had high hopes for a "fragile but efficient peace process" in east Ukraine, where pro-Russian separatists have been battling Ukrainian government forces since April.
A cease-fire agreement, signed last week in the Belarusian capital of Minsk, has been riddled with violations from the start.
But the deal has helped reduce casualties and brought dozens of prisoners on each side home.
Near midnight on Friday, 33 Russian trucks crossed into Ukraine carrying humanitarian aid for the hard-hit east, Russian customs official Rayan Farkushin was quoted as saying by the Interfax and RIA Novosti news agencies.
A previous Russian humanitarian convoy caused controversy when it entered Ukraine unilaterally in August; Ukrainian officials worried it was cover for bringing in aid to the rebels or spiriting away industrial equipment seized by the rebels.
But the Minsk agreement provided for two additional convoys.
Russian officials said the aid would include food, water purifiers and electrical generators.
Ukrainian troops and Russian-backed rebel forces on Friday exchanged 67 prisoners who had been captured in eastern Ukraine.
The transfer, including Russian citizens who served as insurgents, took place outside the main rebel stronghold of Donetsk under the watch of international observers.
Poroshenko has struggled to paint the truce — struck amid a major rebel offensive against Ukrainian forces in the region — as a victory.
The prisoner exchange has been a key pillar of Poroshenko's argument that Ukraine can benefit by striking a deal with the rebels.
Thirty-six Ukrainian servicemen were released after negotiations, Poroshenko said.
Ukrainian forces handed over 31 rebels detained over the five-month conflict.
Shortly after the prisoner exchange, a volley of rocket fire was heard in Donetsk, an almost daily occurrence since the cease-fire went into effect.
The Ukrainian servicemen were driven away from local rebel headquarters around 1:30 a.m. and taken several miles (kilometers) north of Donetsk, where they were met by Ukrainian military officials.
The two sets of captives were brought out wearing handcuffs, which were removed as they were handed over.
One representative from each side checked each prisoner against a list and crossed out names as they were freed.
"There is an ongoing process of talks. We are meeting each other's demands and fulfilling our promises," said Yuriy Tandit, a negotiator for the government.
Darya Morozova, who is overseeing the prisoner exchange for the separatists, estimates around 1,200 rebels and their supporters are being detained by Ukrainian authorities.
She said the rebels were holding "up to 1,000" people.
Morozova claimed the rebel prisoners had been poorly treated and some had not been fed for around two weeks.
Another transfer of prisoners is expected in the next three days, she said.
One freed prisoner, Simon Veridya from Moscow, said he was captured in the town of Kramatorsk, which was retaken by government forces in July.
"They shot at our ambulance. There were five of us, including two women. We were taken into custody in Kramatorsk" at the airport, Veridya said.
"I was beaten and have two broken ribs."
The conflict has been raging since mid-April, claiming more than 3,000 lives, according to the UN.
Hundreds of thousands have fled from the fighting. Ukraine and the West have accused Russia of propping up the insurgency in eastern Ukraine with recruits and heavy weapons.
Moscow has admitted that Russian volunteers were fighting across the border but denied sending the rebels weapons or troops.
In Brussels, the European Union toughened financial penalties on Russian banks, arms manufacturers and its biggest oil company, Rosneft.
The Obama administration said Friday that it is sanctioning Russia's largest bank and expanding sanctions targeting Russia's energy and defense sectors.
The EU measures, effective Friday, broaden the scope of penalties imposed in July.
They increase restrictions to Europe's capital markets, further limiting the targeted Russian companies' ability to raise money.
They now also apply to major oil and defense companies.
The EU sanctions forbid EU companies from engaging in new contracts in oil drilling, exploration and related services in Russia's Arctic, deep sea and shale oil projects.
Russia's Rosneft is majority-owned by the state, but Britain's BP holds a 19.75 percent stake in it.
The sanctions ban 24 more officials from traveling to the EU and freeze their assets there — including four deputy parliament speakers and leaders of the separatists in eastern Ukraine.
They also hit Sergei Chemezov, a chairman of a state-owned industrial giant and a former Soviet intelligence officer who served alongside Russian President Vladimir Putin in his previous roles during the Cold War.
Speaking in Kiev on Friday, European Parliament President Martin Schulz said the new sanctions signaled to Moscow that there is "no return to business as usual."
In Kiev, Poroshenko thanked the EU for the new sanctions.
"A friend in need is a friend indeed," Poroshenko said.
"I feel a full part of the European Union family," he added.