Poland's spat over who should lead the European Council is set to overshadow a meeting of EU leaders this week that was meant to forge unity in the bloc when Britain quits.
So, too, does the Polish government believe Tusk is using his European Council presidency to interfere in Poland's domestic politics.
Tusk, a former prime minister, tweeted his thanks for the support.
The Polish government has decided "to veto" the conclusions of the council after 27 leaders of the European Union re-elected Donald Tusk for a second term as president of the European Council.
Sources suggested that 27 of the 28 European Union states had backed Tusk in the vote.
"One can only hope that the conflict will be resolved so we don't have a great divide in Europe", Gabriel said, when asked about Poland's stance on Tusk.
Polish Prime Minister Beata Szydlo said last week that they "never will" agree to such divisions while Slovakian premier Robert Fico said preparations for Rome were "pathetic".
Poland's euro sceptic government on Saturday proposed MEP Jacek Saryusz-Wolski as its official candidate to replace Tusk.
Party leader Jaroslaw Kaczinski said in 2012 he held Tusk "politically" accountable for the death of his twin brother, then Poland's president Lech Kaczynski, who was killed along with other 95 people in a plane crash in Russian Federation in 2010.
Jarosław Kaczyński (C) is the leader of the ruling party in Poland.
Maltese prime minister Joseph Muscat chaired the session to decide Mr Tusk's mandate.
"I see his re-election as a sign of stability for the entire European Union and I look forward to continuing working with him", Mrs Merkel said.
EU powerhouses France and Germany on Monday endorsed the idea of a "multi-speed" EU in which some members could deepen their integration faster than others, a move that Poland and other eastern EU countries staunchly oppose.
According to Tusk, one of the key summit objectives will be on jobs, growth and competitiveness while the benefits of "widely and fairly" spread economic growth will also be stressed.