A European Commission spokesman said while progress was made on Sunday, "significant gaps" remained.
Europe wants Greece to make spending cuts worth €2bn (£1.44bn), to secure a deal that will unlock bailout funds.
Greek deputy prime minister Yannis Dragasakis said that Athens was still ready to negotiate with its lenders.
He said Greek government proposals submitted on Sunday had fully covered the fiscal deficit as demanded.
However, Mr Dragasakis added that the EU and IMF still wanted Greece to cut pensions - something Athens has said it would never accept.
IMF chief economist Olivier Blanchard said in a blog post that an agreement will require "difficult decisions", with "tough choices and tough commitments to be made on both sides".
The cash-strapped nation is trying to agree a funding deal with the European Union and IMF before the end of June to avoid a default.
Eurozone finance ministers will discuss Greece when they meet on Thursday. The gathering is regarded as Greece's last chance to strike a deal.
The Commission spokesman said: "President [Jean-Claude] Juncker remains convinced that with stronger reform efforts on the Greek side and political will on all sides, a solution can still be found before the end of the month."
The talks come as Germany ramps up pressure on Greece. Vice-chancellor Sigmar Gabriel said on Sunday that European nations were losing patience with Greece.
Germany wanted to keep Greece in the eurozone, but writing in Bild he warned that "not only is time running out, but so too is patience across Europe".
Mr Gabriel is also economy minister and head of junior coalition partners the Social Democrats.
His article is seen as a warning, particularly as his party has been more sympathetic to Greece in the past.
"Everywhere in Europe, the sentiment is growing that enough is enough," he wrote.
Greece is seeking to avoid defaulting on a €1.5bn debt repayment to the IMF due by the end of the month.
Creditors have demanded cuts in spending in return for another tranche of bailout funds.
But Greece's ruling left-wing Syriza party, led by Alexis Tsipras, was elected in January on promises to ease up on the highly unpopular austerity measures, increase the minimum monthly wage and create more jobs.
However, on Saturday Mr Tsipras warned the Greek people to prepare for a "difficult compromise".
€320bn
Greece's debt mountain
€240bn
European bailout
€56bn Greece owes Germany
177% country's debt-to-GDP ratio
25% fall in GDP since 2010
26% Greek unemployment rate
How serious for us is the Greek tragedy?

It comes amid growing concern that the next branch of so-called Islamic State (IS) could emerge in the region.
David Cameron said "brutal terrorists" would only be defeated if countries united against their "common enemy".
Mr Cameron is to raise the issue in meetings with the leaders of both countries during the four-day trip.
He is heading to Indonesia on the first stop of his tour, which is primarily intended to boost trade with Britain.
But Mr Cameron will also use his visit to discuss the threat from Islamist extremism with his counterparts, President Joko Widodo of Indonesia, and later Prime Minister Najib Razak of Malaysia.
The UK government estimates about 500 people from Indonesia and about 200 from Malaysia have joined IS in Iraq and Syria.
The prime minister is said to be "keen to explore" whether the UK can offer more practical counter-terrorism support to both countries, such as disrupting foreign fighters, investigating potential terror plots and improving aviation security.
He is also planning to learn from their work in tackling the extremist ideology and encouraging tolerance, to explore whether the UK can learn from their approach.
Speaking ahead of his departure for Indonesia, Mr Cameron said IS was "one of the biggest threats our world has faced".
"All of us face a threat from foreign fighters and from increasing radicalisation within our countries and it's right that we look at what help we can provide to one another," he said.
Separately, it is understood the UK government has had discussions about its role in tackling IS in Libya.
There is no suggestion of any air strikes but it is thought the UK has considered what help it could offer in combating IS's presence if a stable Libyan government was formed.
The latest round of talks between Greek and EU officials in Brussels has failed to reach an agreement.
[NEXT_CONCEPT]
The prime minister is expected to offer Indonesia and Malaysia support in tackling Islamist extremists, during a trade mission to South East Asia.