"Negotiations on the reform plan have fallen behind, which is in nobody's interest," he said today, cited by the Avghi daily, close to Tspiras' Syriza party.
Greece sent creditors its pension reform plans at the start of January but "to date we have had no official response from the institutions, which is due to disagreements at their heart," Tsipras asserted.
Facing fears it may yet have to quit the eurozone, cash-strapped Greece is under mounting pressure to deliver credible reforms, notably on pensions, International Monetary Fund European zone head Poul Thomsen said last week.
Ten days ago, a first round of talks held in Athens between creditors and Greek authorities proved inconclusive.
Also Read
The Greek government says further talks will be held soon.
But Thomsen's comments last week warned against "over-optimistic assumptions (which) will soon cause Grexit fears to resurface once again and stifle the investment climate."
He added that pension reforms were crucial -- Greece spends some 17 per cent of GDP on pensions according to Eurostat, more than any other EU member.
But in July the EU stepped in with a new EUR 86 billion of financial aid programme -- which the IMF has not joined -- in exchange for economic measures and pension reform, still the subject of hot debate.
Athens responded to Thomsen's concerns by accusing the IMF of "demanding the application of a radically different programme than that agreed" by Greece and its eurozone partners last year.
He added that "Europe cannot continue discussing unreachable (budgetary) objectives, especially now, when it is facing important challenges such as the migration crisis" stemming from the conflict in Syria.