ISTANBUL — Prime Minister Recep Tayyip Erdogan returned to his country early Friday morning and was met at the airport by tens of thousands of supporters who offered a boisterous counterpoint to the demonstrations that for nearly a week have occupied Taksim Square in central Istanbul and presented Mr. Erdogan with the gravest political crisis of his decade in power.

Flanked by his wife, Mr. Erdogan made his way through the crowd, boarded a bus and grabbed a microphone to deliver an emphatic speech in which he gave no ground to his opponents, calling them vandals and saying the demonstrations must end. He also sought to position himself as a leader of all Turks.

“Tonight is not only you,” he said. “I am addressing everyone in every city of Turkey.”

Invoking his faith and those of his followers, he said, “Nobody can stop Turkey’s rise but Allah.”

Mr. Erdogan’s supporters, which state news media estimated in the tens of thousands, waved placards and chanted, “We are the soldiers of Erdogan!” and “Istanbul is here, where are the looters?”