President Reagan's stand in the air controllers strike pushed the dollar above the 6-franc level in Paris yesterday for the first time and boosted it on other European money markets despite massive dumping of dollars by central banks.

Gold hit the $400 mark as the official Soviet news agency issued a stern warning to the Polish workers union.

In Zurich gold was $1 an ounce higher at $393.50. At the close in London it had risen to $395.50 an ounce from $392.50 Wednesday.

In New York, however, a buying surge at the close pushed gold to $399 from $392.25. The New York Commodity Exchange settlement price for gold was $400 even, up from $391.20. Silver surged to $8.68 an ounce from $8.315, and it settled on the Comex at $8.68, up from $8.315.

The dollar closed in Paris at a record 6.0175 francs, up from Wednesday's 5.9925.

In Frankfurt, the dollar hit a five-year high of 2.5250 marks, up from 2.50775.

In London, the pound fell to $1.7980 from $1.8060, although it came back a bit in New York to $1.8025.

In Tokyo, massive central bank buying, helped by selling on the part of Japanee importers, pushed the dollar down to 240 yen from 242.90.