If the agreement reached Monday evening is approved by the German government as a whole, "we will be obliged to take measures to avoid disadvantages for Austria and its people," the Austrian government said in a statement.
It added it would be "ready to take measures to protect our southern borders in particular," those with Italy and Slovenia.
German Chancellor Angela Merkel reached a compromise deal Monday on migration with her rebellious interior minister, Horst Seehofer, to defuse a bitter row that had threatened her government.
Among the proposals is a plan to send back to Austria asylum seekers arriving in Germany who cannot be returned to their countries of entry into the European Union.
Austria said it would be prepared to take similar measures to block asylum seekers at its southern borders, with the risk of a domino effect in Europe.
"We are now waiting for a rapid clarification of the German position at a federal level," said the statement, signed by Austria's conservative
Chancellor Sebastian Kurz and his allies of the far-right Freedom party, Vice Chancellor Heinz-Christian Strache and Interior Minister Herbert Kickl.
"German considerations prove once again the importance of a common European protection of the external borders," the statement said.
Kurz on Tuesday is to present before the European Parliament in Strasbourg his priorities for Austria's six-month presidency of the European Union, with the issue of migration expected to feature prominently.