Pusic made the statement before a regular monthly working lunch with ambassadors from neighbouring countries.
Pusic said that the EU's position that the runaway general Ante Gotovina must be handed over to the Hague war crimes tribunal had become very radical since December, when the European Council set March 17 as the date for the start of Croatia's EU entry talks.
"That position has grown stronger and more widespread because it is now backed by all EU member-states," Pusic said, adding that the term "full cooperation" with the Hague tribunal now meant exclusively Gotovina's transfer to The Hague.
"We should use the next thirty days to make maximum efforts because a postponement of the talks until October would be very unfavourable for us," Pusic said.
She added that Turkey would start its entry talks on October 2, which would be very complicated and may not end in EU membership, so Croatia's position could be more difficult then if it started talks sooner and separately.
In case Croatia starts the talks at the same time as Turkey, it should insist on pre-screening to speed up the negotiating process, Pusic said.
Participants in working lunches in the parliament discuss the development of relations between Croatia and neighbouring countries, including topics of mutual interest, in which case a special guest is invited.
Today's topic was the continuation of the process of Croatia's integration with the EU and a possible postponement of the entry talks. The special guest was Dutch Ambassador Lionel Strenghart Veer, who attended the meeting also as a representative of Luxembourg, the country chairing the EU.
Veer told reporters that the Dutch government supported Croatia in its integration with the EU, but that full cooperation with the Hague tribunal remained a big problem which had to be solved if the talks were to start on March 17.
Along with Pusic and Veer, the meeting was attended by ambassadors Zlatko Dizdarevic of Bosnia-Herzegovina, Alessandro Grafini of Italy, Laszlo Mohai of Hungary, Peter Andrej Bekes of Slovenia, and Milan Simurdic of Serbia and Montenegro.