That mattered to Athens, which argued that by using the name Macedonia, the country was implying it had a claim to the Greek region. If the agreement is confirmed again, the president would be legally required to sign off on it.
The people's nationality will be defined as "Macedonian/Citizens of the Republic of North Macedonia".
A special commission will agree on the use of trade marks with geographic denominator by both sides.
Similarly, Greek opposition parties, and even one of Tsipras's partner parties, called the agreement a disgrace. Ivanov would have to sign off on the agreement if it passed a second time. Opponents in Macedonia disagreed with any modification to their country's name, seeing it as a threat to their national identity. "That which we call a rose, by any other word would smell as sweet". If the result is negative, early parliamentary elections will be called. Thanks to you the impossible is becoming possible.
'I am keeping my fingers crossed, ' he said.
Athens and Skopje reached a historic accord on Tuesday agreeing to call the former Yugoslav nation the "Republic of Northern Macedonia", settling almost three decades of disagreement over its name.
"It's clear that (Macedonia) bears no relation to the ancient (Macedonian) culture... and that their language belongs to the Slavic language", he said.
Texas-based Maya Panova of the Forum for Democratic Macedonia, a fellow diaspora organization, said that although many Macedonian emigrés welcomed Tuesday's announcement of a possible resolution, they are also not surprised by Ivanov's move to block its ratification.
Athens and Skopje are aiming to agree the broad outline of a settlement before an European Union summit in late June, though any deal would need to clear a referendum in Macedonia and win approval from lawmakers in both countries.
"We just saw a press conference where the defeat is shown as a fake victory", Hristijan Mickoski, president of opposition party VMRO-DPMNE said. For 27 years, Greece and Macedonia have been bedeviled by one of the oddest disputes in global diplomacy - what the smaller, younger and landlocked country of 2.1 million should be called, at home and overseas.
Tsipras said his country would support both of Zaev's wishes, pending the successful revision of its northern neighbour's constitution.More news: Birthday boy Salah left on the bench for Egypt's World Cup opener
Past experiences in the Balkans suggest that it is perhaps unwise to give too much credit when so many things could derail the process.
This year there have been several protests against an agreement in Athens, Thessaloniki and Skopje. Opponents of a name-change deal have staged rallies in Greece and Macedonia over the past few months.
In Greece, Tsipras' conservative rival Kyriakos Mitsotakis also denounced the deal as a "bad agreement".
Ivanov then told the public the deal was a "personal" matter of Zaev and Dimitrov and accused them of not seeking to reach consensus on the issue.
The EU's enlargement commissioner, Johannes Hahn, and the EU foreign policy chief, Federica Mogherini, enthusiastically welcomed the breakthrough, which is expected to unlock Skopje's stalled EU and North Atlantic Treaty Organisation membership bids.
United Nations secretary general Antonio Guterres praised the agreement as "a demonstration of leadership to the wider region and beyond" and hopes it will inspire others involved in drawn-out conflicts "to work towards negotiated settlements without further delay", his spokesman Stephane Dujarric said.
"We have lost, we retreated", said 40-year old Stamatia Valtadorou, a private sector employee.
Macedonian PM Zoran Zaev addresses the media about the "name" agreement with Greece.
A man holds a Greek flag next to a statue of Alexander the Great.
Upon the breakup of the former Yugoslavia in 1991, Macedonia, one of the six constituent republics in the defunct federation, declared itself a new nation. The Bulgarian dialect spoken there was gradually filled with Serbian words. A monument to Alexander the Great is seen in the center of Skopje on Sunday.
Later in the day, about 1,000 people gathered in front of the parliament building in Skopje, calling for Prime Minister Zoran Zaev's resignation.